// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Copyright (C) 1993  Linus Torvalds
 *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
 *  SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
 *  Major rework to support vmap/vunmap, Christoph Hellwig, SGI, August 2002
 *  Numa awareness, Christoph Lameter, SGI, June 2005
 *  Improving global KVA allocator, Uladzislau Rezki, Sony, May 2019
 */

#include <generated/deconfig.h> 
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/highmem.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/set_memory.h>
#include <linux/debugobjects.h>
#include <linux/kallsyms.h>
#include <linux/list.h>
#include <linux/notifier.h>
#include <linux/rbtree.h>
#include <linux/xarray.h>
#include <linux/rcupdate.h>
#include <linux/pfn.h>
#include <linux/kmemleak.h>
#include <linux/atomic.h>
#include <linux/compiler.h>
#include <linux/llist.h>
#include <linux/bitops.h>
#include <linux/rbtree_augmented.h>
#include <linux/overflow.h>

#include <linux/uaccess.h>
#include <asm/tlbflush.h>
#include <asm/shmparam.h>

#include "internal.h"
#include "pgalloc-track.h"

//bool is_vmalloc_addr(const void *x)
//{
//	unsigned long addr = (unsigned long)x;

//	return addr >= VMALLOC_START && addr < VMALLOC_END;
//}
//EXPORT_SYMBOL(is_vmalloc_addr);

//struct vfree_deferred {
//	struct llist_head list;
//	struct work_struct wq;
//};
//static DEFINE_PER_CPU(struct vfree_deferred, vfree_deferred);

//static void __vunmap(const void *, int);

//static void free_work(struct work_struct *w)
//{
//	struct vfree_deferred *p = container_of(w, struct vfree_deferred, wq);
//	struct llist_node *t, *llnode;

//	llist_for_each_safe(llnode, t, llist_del_all(&p->list))
//		__vunmap((void *)llnode, 1);
//}

///*** Page table manipulation functions ***/

//static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
//			     pgtbl_mod_mask *mask)
//{
//	pte_t *pte;

//	pte = pte_offset_kernel(pmd, addr);
//	do {
//		pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
//		WARN_ON(!pte_none(ptent) && !pte_present(ptent));
//	} while (pte++, addr += PAGE_SIZE, addr != end);
//	*mask |= PGTBL_PTE_MODIFIED;
//}

//static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
//			     pgtbl_mod_mask *mask)
//{
//	pmd_t *pmd;
//	unsigned long next;
//	int cleared;

//	pmd = pmd_offset(pud, addr);
//	do {
//		next = pmd_addr_end(addr, end);

//		cleared = pmd_clear_huge(pmd);
//		if (cleared || pmd_bad(*pmd))
//			*mask |= PGTBL_PMD_MODIFIED;

//		if (cleared)
//			continue;
//		if (pmd_none_or_clear_bad(pmd))
//			continue;
//		vunmap_pte_range(pmd, addr, next, mask);

//		cond_resched();
//	} while (pmd++, addr = next, addr != end);
//}

//static void vunmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
//			     pgtbl_mod_mask *mask)
//{
//	pud_t *pud;
//	unsigned long next;
//	int cleared;

//	pud = pud_offset(p4d, addr);
//	do {
//		next = pud_addr_end(addr, end);

//		cleared = pud_clear_huge(pud);
//		if (cleared || pud_bad(*pud))
//			*mask |= PGTBL_PUD_MODIFIED;

//		if (cleared)
//			continue;
//		if (pud_none_or_clear_bad(pud))
//			continue;
//		vunmap_pmd_range(pud, addr, next, mask);
//	} while (pud++, addr = next, addr != end);
//}

//static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
//			     pgtbl_mod_mask *mask)
//{
//	p4d_t *p4d;
//	unsigned long next;
//	int cleared;

//	p4d = p4d_offset(pgd, addr);
//	do {
//		next = p4d_addr_end(addr, end);

//		cleared = p4d_clear_huge(p4d);
//		if (cleared || p4d_bad(*p4d))
//			*mask |= PGTBL_P4D_MODIFIED;

//		if (cleared)
//			continue;
//		if (p4d_none_or_clear_bad(p4d))
//			continue;
//		vunmap_pud_range(p4d, addr, next, mask);
//	} while (p4d++, addr = next, addr != end);
//}

///**
// * unmap_kernel_range_noflush - unmap kernel VM area
// * @start: start of the VM area to unmap
// * @size: size of the VM area to unmap
// *
// * Unmap PFN_UP(@size) pages at @addr.  The VM area @addr and @size specify
// * should have been allocated using get_vm_area() and its friends.
// *
// * NOTE:
// * This function does NOT do any cache flushing.  The caller is responsible
// * for calling flush_cache_vunmap() on to-be-mapped areas before calling this
// * function and flush_tlb_kernel_range() after.
// */
//void unmap_kernel_range_noflush(unsigned long start, unsigned long size)
//{
//	unsigned long end = start + size;
//	unsigned long next;
//	pgd_t *pgd;
//	unsigned long addr = start;
//	pgtbl_mod_mask mask = 0;

//	BUG_ON(addr >= end);
//	pgd = pgd_offset_k(addr);
//	do {
//		next = pgd_addr_end(addr, end);
//		if (pgd_bad(*pgd))
//			mask |= PGTBL_PGD_MODIFIED;
//		if (pgd_none_or_clear_bad(pgd))
//			continue;
//		vunmap_p4d_range(pgd, addr, next, &mask);
//	} while (pgd++, addr = next, addr != end);

//	if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
//		arch_sync_kernel_mappings(start, end);
//}

//static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
//		unsigned long end, pgprot_t prot, struct page **pages, int *nr,
//		pgtbl_mod_mask *mask)
//{
//	pte_t *pte;

//	/*
//	 * nr is a running index into the array which helps higher level
//	 * callers keep track of where we're up to.
//	 */

//	pte = pte_alloc_kernel_track(pmd, addr, mask);
//	if (!pte)
//		return -ENOMEM;
//	do {
//		struct page *page = pages[*nr];

//		if (WARN_ON(!pte_none(*pte)))
//			return -EBUSY;
//		if (WARN_ON(!page))
//			return -ENOMEM;
//		set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
//		(*nr)++;
//	} while (pte++, addr += PAGE_SIZE, addr != end);
//	*mask |= PGTBL_PTE_MODIFIED;
//	return 0;
//}

//static int vmap_pmd_range(pud_t *pud, unsigned long addr,
//		unsigned long end, pgprot_t prot, struct page **pages, int *nr,
//		pgtbl_mod_mask *mask)
//{
//	pmd_t *pmd;
//	unsigned long next;

//	pmd = pmd_alloc_track(&init_mm, pud, addr, mask);
//	if (!pmd)
//		return -ENOMEM;
//	do {
//		next = pmd_addr_end(addr, end);
//		if (vmap_pte_range(pmd, addr, next, prot, pages, nr, mask))
//			return -ENOMEM;
//	} while (pmd++, addr = next, addr != end);
//	return 0;
//}

//static int vmap_pud_range(p4d_t *p4d, unsigned long addr,
//		unsigned long end, pgprot_t prot, struct page **pages, int *nr,
//		pgtbl_mod_mask *mask)
//{
//	pud_t *pud;
//	unsigned long next;

//	pud = pud_alloc_track(&init_mm, p4d, addr, mask);
//	if (!pud)
//		return -ENOMEM;
//	do {
//		next = pud_addr_end(addr, end);
//		if (vmap_pmd_range(pud, addr, next, prot, pages, nr, mask))
//			return -ENOMEM;
//	} while (pud++, addr = next, addr != end);
//	return 0;
//}

//static int vmap_p4d_range(pgd_t *pgd, unsigned long addr,
//		unsigned long end, pgprot_t prot, struct page **pages, int *nr,
//		pgtbl_mod_mask *mask)
//{
//	p4d_t *p4d;
//	unsigned long next;

//	p4d = p4d_alloc_track(&init_mm, pgd, addr, mask);
//	if (!p4d)
//		return -ENOMEM;
//	do {
//		next = p4d_addr_end(addr, end);
//		if (vmap_pud_range(p4d, addr, next, prot, pages, nr, mask))
//			return -ENOMEM;
//	} while (p4d++, addr = next, addr != end);
//	return 0;
//}

///**
// * map_kernel_range_noflush - map kernel VM area with the specified pages
// * @addr: start of the VM area to map
// * @size: size of the VM area to map
// * @prot: page protection flags to use
// * @pages: pages to map
// *
// * Map PFN_UP(@size) pages at @addr.  The VM area @addr and @size specify should
// * have been allocated using get_vm_area() and its friends.
// *
// * NOTE:
// * This function does NOT do any cache flushing.  The caller is responsible for
// * calling flush_cache_vmap() on to-be-mapped areas before calling this
// * function.
// *
// * RETURNS:
// * 0 on success, -errno on failure.
// */
//int map_kernel_range_noflush(unsigned long addr, unsigned long size,
//			     pgprot_t prot, struct page **pages)
//{
//	unsigned long start = addr;
//	unsigned long end = addr + size;
//	unsigned long next;
//	pgd_t *pgd;
//	int err = 0;
//	int nr = 0;
//	pgtbl_mod_mask mask = 0;

//	BUG_ON(addr >= end);
//	pgd = pgd_offset_k(addr);
//	do {
//		next = pgd_addr_end(addr, end);
//		if (pgd_bad(*pgd))
//			mask |= PGTBL_PGD_MODIFIED;
//		err = vmap_p4d_range(pgd, addr, next, prot, pages, &nr, &mask);
//		if (err)
//			return err;
//	} while (pgd++, addr = next, addr != end);

//	if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
//		arch_sync_kernel_mappings(start, end);

//	return 0;
//}

//int map_kernel_range(unsigned long start, unsigned long size, pgprot_t prot,
//		struct page **pages)
//{
//	int ret;

//	ret = map_kernel_range_noflush(start, size, prot, pages);
//	flush_cache_vmap(start, start + size);
//	return ret;
//}

//int is_vmalloc_or_module_addr(const void *x)
//{
//	/*
//	 * ARM, x86-64 and sparc64 put modules in a special place,
//	 * and fall back on vmalloc() if that fails. Others
//	 * just put it in the vmalloc space.
//	 */
//#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
//	unsigned long addr = (unsigned long)x;
//	if (addr >= MODULES_VADDR && addr < MODULES_END)
//		return 1;
//#endif
//	return is_vmalloc_addr(x);
//}

///*
// * Walk a vmap address to the struct page it maps.
// */
//struct page *vmalloc_to_page(const void *vmalloc_addr)
//{
//	unsigned long addr = (unsigned long) vmalloc_addr;
//	struct page *page = NULL;
//	pgd_t *pgd = pgd_offset_k(addr);
//	p4d_t *p4d;
//	pud_t *pud;
//	pmd_t *pmd;
//	pte_t *ptep, pte;

//	/*
//	 * XXX we might need to change this if we add VIRTUAL_BUG_ON for
//	 * architectures that do not vmalloc module space
//	 */
//	VIRTUAL_BUG_ON(!is_vmalloc_or_module_addr(vmalloc_addr));

//	if (pgd_none(*pgd))
//		return NULL;
//	p4d = p4d_offset(pgd, addr);
//	if (p4d_none(*p4d))
//		return NULL;
//	pud = pud_offset(p4d, addr);

//	/*
//	 * Don't dereference bad PUD or PMD (below) entries. This will also
//	 * identify huge mappings, which we may encounter on architectures
//	 * that define CONFIG_HAVE_ARCH_HUGE_VMAP=y. Such regions will be
//	 * identified as vmalloc addresses by is_vmalloc_addr(), but are
//	 * not [unambiguously] associated with a struct page, so there is
//	 * no correct value to return for them.
//	 */
//	WARN_ON_ONCE(pud_bad(*pud));
//	if (pud_none(*pud) || pud_bad(*pud))
//		return NULL;
//	pmd = pmd_offset(pud, addr);
//	WARN_ON_ONCE(pmd_bad(*pmd));
//	if (pmd_none(*pmd) || pmd_bad(*pmd))
//		return NULL;

//	ptep = pte_offset_map(pmd, addr);
//	pte = *ptep;
//	if (pte_present(pte))
//		page = pte_page(pte);
//	pte_unmap(ptep);
//	return page;
//}
//EXPORT_SYMBOL(vmalloc_to_page);

///*
// * Map a vmalloc()-space virtual address to the physical page frame number.
// */
//unsigned long vmalloc_to_pfn(const void *vmalloc_addr)
//{
//	return page_to_pfn(vmalloc_to_page(vmalloc_addr));
//}
//EXPORT_SYMBOL(vmalloc_to_pfn);


///*** Global kva allocator ***/

//#define DEBUG_AUGMENT_PROPAGATE_CHECK 0
//#define DEBUG_AUGMENT_LOWEST_MATCH_CHECK 0


//static DEFINE_SPINLOCK(vmap_area_lock);
//static DEFINE_SPINLOCK(free_vmap_area_lock);
///* Export for kexec only */
//LIST_HEAD(vmap_area_list);
//static LLIST_HEAD(vmap_purge_list);
//static struct rb_root vmap_area_root = RB_ROOT;
//static bool vmap_initialized __read_mostly;

///*
// * This kmem_cache is used for vmap_area objects. Instead of
// * allocating from slab we reuse an object from this cache to
// * make things faster. Especially in "no edge" splitting of
// * free block.
// */
//static struct kmem_cache *vmap_area_cachep;

///*
// * This linked list is used in pair with free_vmap_area_root.
// * It gives O(1) access to prev/next to perform fast coalescing.
// */
//static LIST_HEAD(free_vmap_area_list);

///*
// * This augment red-black tree represents the free vmap space.
// * All vmap_area objects in this tree are sorted by va->va_start
// * address. It is used for allocation and merging when a vmap
// * object is released.
// *
// * Each vmap_area node contains a maximum available free block
// * of its sub-tree, right or left. Therefore it is possible to
// * find a lowest match of free area.
// */
//static struct rb_root free_vmap_area_root = RB_ROOT;

///*
// * Preload a CPU with one object for "no edge" split case. The
// * aim is to get rid of allocations from the atomic context, thus
// * to use more permissive allocation masks.
// */
//static DEFINE_PER_CPU(struct vmap_area *, ne_fit_preload_node);

//static __always_inline unsigned long
//va_size(struct vmap_area *va)
//{
//	return (va->va_end - va->va_start);
//}

//static __always_inline unsigned long
//get_subtree_max_size(struct rb_node *node)
//{
//	struct vmap_area *va;

//	va = rb_entry_safe(node, struct vmap_area, rb_node);
//	return va ? va->subtree_max_size : 0;
//}

///*
// * Gets called when remove the node and rotate.
// */
//static __always_inline unsigned long
//compute_subtree_max_size(struct vmap_area *va)
//{
//	return max3(va_size(va),
//		get_subtree_max_size(va->rb_node.rb_left),
//		get_subtree_max_size(va->rb_node.rb_right));
//}

//RB_DECLARE_CALLBACKS_MAX(static, free_vmap_area_rb_augment_cb,
//	struct vmap_area, rb_node, unsigned long, subtree_max_size, va_size)

//static void purge_vmap_area_lazy(void);
//static BLOCKING_NOTIFIER_HEAD(vmap_notify_list);
//static unsigned long lazy_max_pages(void);

//static atomic_long_t nr_vmalloc_pages;

//unsigned long vmalloc_nr_pages(void)
//{
//	return atomic_long_read(&nr_vmalloc_pages);
//}

//static struct vmap_area *__find_vmap_area(unsigned long addr)
//{
//	struct rb_node *n = vmap_area_root.rb_node;

//	while (n) {
//		struct vmap_area *va;

//		va = rb_entry(n, struct vmap_area, rb_node);
//		if (addr < va->va_start)
//			n = n->rb_left;
//		else if (addr >= va->va_end)
//			n = n->rb_right;
//		else
//			return va;
//	}

//	return NULL;
//}

///*
// * This function returns back addresses of parent node
// * and its left or right link for further processing.
// *
// * Otherwise NULL is returned. In that case all further
// * steps regarding inserting of conflicting overlap range
// * have to be declined and actually considered as a bug.
// */
//static __always_inline struct rb_node **
//find_va_links(struct vmap_area *va,
//	struct rb_root *root, struct rb_node *from,
//	struct rb_node **parent)
//{
//	struct vmap_area *tmp_va;
//	struct rb_node **link;

//	if (root) {
//		link = &root->rb_node;
//		if (unlikely(!*link)) {
//			*parent = NULL;
//			return link;
//		}
//	} else {
//		link = &from;
//	}

//	/*
//	 * Go to the bottom of the tree. When we hit the last point
//	 * we end up with parent rb_node and correct direction, i name
//	 * it link, where the new va->rb_node will be attached to.
//	 */
//	do {
//		tmp_va = rb_entry(*link, struct vmap_area, rb_node);

//		/*
//		 * During the traversal we also do some sanity check.
//		 * Trigger the BUG() if there are sides(left/right)
//		 * or full overlaps.
//		 */
//		if (va->va_start < tmp_va->va_end &&
//				va->va_end <= tmp_va->va_start)
//			link = &(*link)->rb_left;
//		else if (va->va_end > tmp_va->va_start &&
//				va->va_start >= tmp_va->va_end)
//			link = &(*link)->rb_right;
//		else {
//			WARN(1, "vmalloc bug: 0x%lx-0x%lx overlaps with 0x%lx-0x%lx\n",
//				va->va_start, va->va_end, tmp_va->va_start, tmp_va->va_end);

//			return NULL;
//		}
//	} while (*link);

//	*parent = &tmp_va->rb_node;
//	return link;
//}

//static __always_inline struct list_head *
//get_va_next_sibling(struct rb_node *parent, struct rb_node **link)
//{
//	struct list_head *list;

//	if (unlikely(!parent))
//		/*
//		 * The red-black tree where we try to find VA neighbors
//		 * before merging or inserting is empty, i.e. it means
//		 * there is no free vmap space. Normally it does not
//		 * happen but we handle this case anyway.
//		 */
//		return NULL;

//	list = &rb_entry(parent, struct vmap_area, rb_node)->list;
//	return (&parent->rb_right == link ? list->next : list);
//}

//static __always_inline void
//link_va(struct vmap_area *va, struct rb_root *root,
//	struct rb_node *parent, struct rb_node **link, struct list_head *head)
//{
//	/*
//	 * VA is still not in the list, but we can
//	 * identify its future previous list_head node.
//	 */
//	if (likely(parent)) {
//		head = &rb_entry(parent, struct vmap_area, rb_node)->list;
//		if (&parent->rb_right != link)
//			head = head->prev;
//	}

//	/* Insert to the rb-tree */
//	rb_link_node(&va->rb_node, parent, link);
//	if (root == &free_vmap_area_root) {
//		/*
//		 * Some explanation here. Just perform simple insertion
//		 * to the tree. We do not set va->subtree_max_size to
//		 * its current size before calling rb_insert_augmented().
//		 * It is because of we populate the tree from the bottom
//		 * to parent levels when the node _is_ in the tree.
//		 *
//		 * Therefore we set subtree_max_size to zero after insertion,
//		 * to let __augment_tree_propagate_from() puts everything to
//		 * the correct order later on.
//		 */
//		rb_insert_augmented(&va->rb_node,
//			root, &free_vmap_area_rb_augment_cb);
//		va->subtree_max_size = 0;
//	} else {
//		rb_insert_color(&va->rb_node, root);
//	}

//	/* Address-sort this list */
//	list_add(&va->list, head);
//}

//static __always_inline void
//unlink_va(struct vmap_area *va, struct rb_root *root)
//{
//	if (WARN_ON(RB_EMPTY_NODE(&va->rb_node)))
//		return;

//	if (root == &free_vmap_area_root)
//		rb_erase_augmented(&va->rb_node,
//			root, &free_vmap_area_rb_augment_cb);
//	else
//		rb_erase(&va->rb_node, root);

//	list_del(&va->list);
//	RB_CLEAR_NODE(&va->rb_node);
//}

//#if DEBUG_AUGMENT_PROPAGATE_CHECK
//static void
//augment_tree_propagate_check(void)
//{
//	struct vmap_area *va;
//	unsigned long computed_size;

//	list_for_each_entry(va, &free_vmap_area_list, list) {
//		computed_size = compute_subtree_max_size(va);
//		if (computed_size != va->subtree_max_size)
//			pr_emerg("tree is corrupted: %lu, %lu\n",
//				va_size(va), va->subtree_max_size);
//	}
//}
//#endif

///*
// * This function populates subtree_max_size from bottom to upper
// * levels starting from VA point. The propagation must be done
// * when VA size is modified by changing its va_start/va_end. Or
// * in case of newly inserting of VA to the tree.
// *
// * It means that __augment_tree_propagate_from() must be called:
// * - After VA has been inserted to the tree(free path);
// * - After VA has been shrunk(allocation path);
// * - After VA has been increased(merging path).
// *
// * Please note that, it does not mean that upper parent nodes
// * and their subtree_max_size are recalculated all the time up
// * to the root node.
// *
// *       4--8
// *        /\
// *       /  \
// *      /    \
// *    2--2  8--8
// *
// * For example if we modify the node 4, shrinking it to 2, then
// * no any modification is required. If we shrink the node 2 to 1
// * its subtree_max_size is updated only, and set to 1. If we shrink
// * the node 8 to 6, then its subtree_max_size is set to 6 and parent
// * node becomes 4--6.
// */
//static __always_inline void
//augment_tree_propagate_from(struct vmap_area *va)
//{
//	/*
//	 * Populate the tree from bottom towards the root until
//	 * the calculated maximum available size of checked node
//	 * is equal to its current one.
//	 */
//	free_vmap_area_rb_augment_cb_propagate(&va->rb_node, NULL);

//#if DEBUG_AUGMENT_PROPAGATE_CHECK
//	augment_tree_propagate_check();
//#endif
//}

//static void
//insert_vmap_area(struct vmap_area *va,
//	struct rb_root *root, struct list_head *head)
//{
//	struct rb_node **link;
//	struct rb_node *parent;

//	link = find_va_links(va, root, NULL, &parent);
//	if (link)
//		link_va(va, root, parent, link, head);
//}

//static void
//insert_vmap_area_augment(struct vmap_area *va,
//	struct rb_node *from, struct rb_root *root,
//	struct list_head *head)
//{
//	struct rb_node **link;
//	struct rb_node *parent;

//	if (from)
//		link = find_va_links(va, NULL, from, &parent);
//	else
//		link = find_va_links(va, root, NULL, &parent);

//	if (link) {
//		link_va(va, root, parent, link, head);
//		augment_tree_propagate_from(va);
//	}
//}

///*
// * Merge de-allocated chunk of VA memory with previous
// * and next free blocks. If coalesce is not done a new
// * free area is inserted. If VA has been merged, it is
// * freed.
// *
// * Please note, it can return NULL in case of overlap
// * ranges, followed by WARN() report. Despite it is a
// * buggy behaviour, a system can be alive and keep
// * ongoing.
// */
//static __always_inline struct vmap_area *
//merge_or_add_vmap_area(struct vmap_area *va,
//	struct rb_root *root, struct list_head *head)
//{
//	struct vmap_area *sibling;
//	struct list_head *next;
//	struct rb_node **link;
//	struct rb_node *parent;
//	bool merged = false;

//	/*
//	 * Find a place in the tree where VA potentially will be
//	 * inserted, unless it is merged with its sibling/siblings.
//	 */
//	link = find_va_links(va, root, NULL, &parent);
//	if (!link)
//		return NULL;

//	/*
//	 * Get next node of VA to check if merging can be done.
//	 */
//	next = get_va_next_sibling(parent, link);
//	if (unlikely(next == NULL))
//		goto insert;

//	/*
//	 * start            end
//	 * |                |
//	 * |<------VA------>|<-----Next----->|
//	 *                  |                |
//	 *                  start            end
//	 */
//	if (next != head) {
//		sibling = list_entry(next, struct vmap_area, list);
//		if (sibling->va_start == va->va_end) {
//			sibling->va_start = va->va_start;

//			/* Free vmap_area object. */
//			kmem_cache_free(vmap_area_cachep, va);

//			/* Point to the new merged area. */
//			va = sibling;
//			merged = true;
//		}
//	}

//	/*
//	 * start            end
//	 * |                |
//	 * |<-----Prev----->|<------VA------>|
//	 *                  |                |
//	 *                  start            end
//	 */
//	if (next->prev != head) {
//		sibling = list_entry(next->prev, struct vmap_area, list);
//		if (sibling->va_end == va->va_start) {
//			/*
//			 * If both neighbors are coalesced, it is important
//			 * to unlink the "next" node first, followed by merging
//			 * with "previous" one. Otherwise the tree might not be
//			 * fully populated if a sibling's augmented value is
//			 * "normalized" because of rotation operations.
//			 */
//			if (merged)
//				unlink_va(va, root);

//			sibling->va_end = va->va_end;

//			/* Free vmap_area object. */
//			kmem_cache_free(vmap_area_cachep, va);

//			/* Point to the new merged area. */
//			va = sibling;
//			merged = true;
//		}
//	}

//insert:
//	if (!merged)
//		link_va(va, root, parent, link, head);

//	/*
//	 * Last step is to check and update the tree.
//	 */
//	augment_tree_propagate_from(va);
//	return va;
//}

//static __always_inline bool
//is_within_this_va(struct vmap_area *va, unsigned long size,
//	unsigned long align, unsigned long vstart)
//{
//	unsigned long nva_start_addr;

//	if (va->va_start > vstart)
//		nva_start_addr = ALIGN(va->va_start, align);
//	else
//		nva_start_addr = ALIGN(vstart, align);

//	/* Can be overflowed due to big size or alignment. */
//	if (nva_start_addr + size < nva_start_addr ||
//			nva_start_addr < vstart)
//		return false;

//	return (nva_start_addr + size <= va->va_end);
//}

///*
// * Find the first free block(lowest start address) in the tree,
// * that will accomplish the request corresponding to passing
// * parameters.
// */
//static __always_inline struct vmap_area *
//find_vmap_lowest_match(unsigned long size,
//	unsigned long align, unsigned long vstart)
//{
//	struct vmap_area *va;
//	struct rb_node *node;
//	unsigned long length;

//	/* Start from the root. */
//	node = free_vmap_area_root.rb_node;

//	/* Adjust the search size for alignment overhead. */
//	length = size + align - 1;

//	while (node) {
//		va = rb_entry(node, struct vmap_area, rb_node);

//		if (get_subtree_max_size(node->rb_left) >= length &&
//				vstart < va->va_start) {
//			node = node->rb_left;
//		} else {
//			if (is_within_this_va(va, size, align, vstart))
//				return va;

//			/*
//			 * Does not make sense to go deeper towards the right
//			 * sub-tree if it does not have a free block that is
//			 * equal or bigger to the requested search length.
//			 */
//			if (get_subtree_max_size(node->rb_right) >= length) {
//				node = node->rb_right;
//				continue;
//			}

//			/*
//			 * OK. We roll back and find the first right sub-tree,
//			 * that will satisfy the search criteria. It can happen
//			 * only once due to "vstart" restriction.
//			 */
//			while ((node = rb_parent(node))) {
//				va = rb_entry(node, struct vmap_area, rb_node);
//				if (is_within_this_va(va, size, align, vstart))
//					return va;

//				if (get_subtree_max_size(node->rb_right) >= length &&
//						vstart <= va->va_start) {
//					node = node->rb_right;
//					break;
//				}
//			}
//		}
//	}

//	return NULL;
//}

//#if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
//#include <linux/random.h>

//static struct vmap_area *
//find_vmap_lowest_linear_match(unsigned long size,
//	unsigned long align, unsigned long vstart)
//{
//	struct vmap_area *va;

//	list_for_each_entry(va, &free_vmap_area_list, list) {
//		if (!is_within_this_va(va, size, align, vstart))
//			continue;

//		return va;
//	}

//	return NULL;
//}

//static void
//find_vmap_lowest_match_check(unsigned long size)
//{
//	struct vmap_area *va_1, *va_2;
//	unsigned long vstart;
//	unsigned int rnd;

//	get_random_bytes(&rnd, sizeof(rnd));
//	vstart = VMALLOC_START + rnd;

//	va_1 = find_vmap_lowest_match(size, 1, vstart);
//	va_2 = find_vmap_lowest_linear_match(size, 1, vstart);

//	if (va_1 != va_2)
//		pr_emerg("not lowest: t: 0x%p, l: 0x%p, v: 0x%lx\n",
//			va_1, va_2, vstart);
//}
//#endif

//enum fit_type {
//	NOTHING_FIT = 0,
//	FL_FIT_TYPE = 1,	/* full fit */
//	LE_FIT_TYPE = 2,	/* left edge fit */
//	RE_FIT_TYPE = 3,	/* right edge fit */
//	NE_FIT_TYPE = 4		/* no edge fit */
//};

//static __always_inline enum fit_type
//classify_va_fit_type(struct vmap_area *va,
//	unsigned long nva_start_addr, unsigned long size)
//{
//	enum fit_type type;

//	/* Check if it is within VA. */
//	if (nva_start_addr < va->va_start ||
//			nva_start_addr + size > va->va_end)
//		return NOTHING_FIT;

//	/* Now classify. */
//	if (va->va_start == nva_start_addr) {
//		if (va->va_end == nva_start_addr + size)
//			type = FL_FIT_TYPE;
//		else
//			type = LE_FIT_TYPE;
//	} else if (va->va_end == nva_start_addr + size) {
//		type = RE_FIT_TYPE;
//	} else {
//		type = NE_FIT_TYPE;
//	}

//	return type;
//}

//static __always_inline int
//adjust_va_to_fit_type(struct vmap_area *va,
//	unsigned long nva_start_addr, unsigned long size,
//	enum fit_type type)
//{
//	struct vmap_area *lva = NULL;

//	if (type == FL_FIT_TYPE) {
//		/*
//		 * No need to split VA, it fully fits.
//		 *
//		 * |               |
//		 * V      NVA      V
//		 * |---------------|
//		 */
//		unlink_va(va, &free_vmap_area_root);
//		kmem_cache_free(vmap_area_cachep, va);
//	} else if (type == LE_FIT_TYPE) {
//		/*
//		 * Split left edge of fit VA.
//		 *
//		 * |       |
//		 * V  NVA  V   R
//		 * |-------|-------|
//		 */
//		va->va_start += size;
//	} else if (type == RE_FIT_TYPE) {
//		/*
//		 * Split right edge of fit VA.
//		 *
//		 *         |       |
//		 *     L   V  NVA  V
//		 * |-------|-------|
//		 */
//		va->va_end = nva_start_addr;
//	} else if (type == NE_FIT_TYPE) {
//		/*
//		 * Split no edge of fit VA.
//		 *
//		 *     |       |
//		 *   L V  NVA  V R
//		 * |---|-------|---|
//		 */
//		lva = __this_cpu_xchg(ne_fit_preload_node, NULL);
//		if (unlikely(!lva)) {
//			/*
//			 * For percpu allocator we do not do any pre-allocation
//			 * and leave it as it is. The reason is it most likely
//			 * never ends up with NE_FIT_TYPE splitting. In case of
//			 * percpu allocations offsets and sizes are aligned to
//			 * fixed align request, i.e. RE_FIT_TYPE and FL_FIT_TYPE
//			 * are its main fitting cases.
//			 *
//			 * There are a few exceptions though, as an example it is
//			 * a first allocation (early boot up) when we have "one"
//			 * big free space that has to be split.
//			 *
//			 * Also we can hit this path in case of regular "vmap"
//			 * allocations, if "this" current CPU was not preloaded.
//			 * See the comment in alloc_vmap_area() why. If so, then
//			 * GFP_NOWAIT is used instead to get an extra object for
//			 * split purpose. That is rare and most time does not
//			 * occur.
//			 *
//			 * What happens if an allocation gets failed. Basically,
//			 * an "overflow" path is triggered to purge lazily freed
//			 * areas to free some memory, then, the "retry" path is
//			 * triggered to repeat one more time. See more details
//			 * in alloc_vmap_area() function.
//			 */
//			lva = kmem_cache_alloc(vmap_area_cachep, GFP_NOWAIT);
//			if (!lva)
//				return -1;
//		}

//		/*
//		 * Build the remainder.
//		 */
//		lva->va_start = va->va_start;
//		lva->va_end = nva_start_addr;

//		/*
//		 * Shrink this VA to remaining size.
//		 */
//		va->va_start = nva_start_addr + size;
//	} else {
//		return -1;
//	}

//	if (type != FL_FIT_TYPE) {
//		augment_tree_propagate_from(va);

//		if (lva)	/* type == NE_FIT_TYPE */
//			insert_vmap_area_augment(lva, &va->rb_node,
//				&free_vmap_area_root, &free_vmap_area_list);
//	}

//	return 0;
//}

///*
// * Returns a start address of the newly allocated area, if success.
// * Otherwise a vend is returned that indicates failure.
// */
//static __always_inline unsigned long
//__alloc_vmap_area(unsigned long size, unsigned long align,
//	unsigned long vstart, unsigned long vend)
//{
//	unsigned long nva_start_addr;
//	struct vmap_area *va;
//	enum fit_type type;
//	int ret;

//	va = find_vmap_lowest_match(size, align, vstart);
//	if (unlikely(!va))
//		return vend;

//	if (va->va_start > vstart)
//		nva_start_addr = ALIGN(va->va_start, align);
//	else
//		nva_start_addr = ALIGN(vstart, align);

//	/* Check the "vend" restriction. */
//	if (nva_start_addr + size > vend)
//		return vend;

//	/* Classify what we have found. */
//	type = classify_va_fit_type(va, nva_start_addr, size);
//	if (WARN_ON_ONCE(type == NOTHING_FIT))
//		return vend;

//	/* Update the free vmap_area. */
//	ret = adjust_va_to_fit_type(va, nva_start_addr, size, type);
//	if (ret)
//		return vend;

//#if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
//	find_vmap_lowest_match_check(size);
//#endif

//	return nva_start_addr;
//}

///*
// * Free a region of KVA allocated by alloc_vmap_area
// */
//static void free_vmap_area(struct vmap_area *va)
//{
//	/*
//	 * Remove from the busy tree/list.
//	 */
//	spin_lock(&vmap_area_lock);
//	unlink_va(va, &vmap_area_root);
//	spin_unlock(&vmap_area_lock);

//	/*
//	 * Insert/Merge it back to the free tree/list.
//	 */
//	spin_lock(&free_vmap_area_lock);
//	merge_or_add_vmap_area(va, &free_vmap_area_root, &free_vmap_area_list);
//	spin_unlock(&free_vmap_area_lock);
//}

///*
// * Allocate a region of KVA of the specified size and alignment, within the
// * vstart and vend.
// */
//static struct vmap_area *alloc_vmap_area(unsigned long size,
//				unsigned long align,
//				unsigned long vstart, unsigned long vend,
//				int node, gfp_t gfp_mask)
//{
//	struct vmap_area *va, *pva;
//	unsigned long addr;
//	int purged = 0;
//	int ret;

//	BUG_ON(!size);
//	BUG_ON(offset_in_page(size));
//	BUG_ON(!is_power_of_2(align));

//	if (unlikely(!vmap_initialized))
//		return ERR_PTR(-EBUSY);

//	might_sleep();
//	gfp_mask = gfp_mask & GFP_RECLAIM_MASK;

//	va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node);
//	if (unlikely(!va))
//		return ERR_PTR(-ENOMEM);

//	/*
//	 * Only scan the relevant parts containing pointers to other objects
//	 * to avoid false negatives.
//	 */
//	kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask);

//retry:
//	/*
//	 * Preload this CPU with one extra vmap_area object. It is used
//	 * when fit type of free area is NE_FIT_TYPE. Please note, it
//	 * does not guarantee that an allocation occurs on a CPU that
//	 * is preloaded, instead we minimize the case when it is not.
//	 * It can happen because of cpu migration, because there is a
//	 * race until the below spinlock is taken.
//	 *
//	 * The preload is done in non-atomic context, thus it allows us
//	 * to use more permissive allocation masks to be more stable under
//	 * low memory condition and high memory pressure. In rare case,
//	 * if not preloaded, GFP_NOWAIT is used.
//	 *
//	 * Set "pva" to NULL here, because of "retry" path.
//	 */
//	pva = NULL;

//	if (!this_cpu_read(ne_fit_preload_node))
//		/*
//		 * Even if it fails we do not really care about that.
//		 * Just proceed as it is. If needed "overflow" path
//		 * will refill the cache we allocate from.
//		 */
//		pva = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node);

//	spin_lock(&free_vmap_area_lock);

//	if (pva && __this_cpu_cmpxchg(ne_fit_preload_node, NULL, pva))
//		kmem_cache_free(vmap_area_cachep, pva);

//	/*
//	 * If an allocation fails, the "vend" address is
//	 * returned. Therefore trigger the overflow path.
//	 */
//	addr = __alloc_vmap_area(size, align, vstart, vend);
//	spin_unlock(&free_vmap_area_lock);

//	if (unlikely(addr == vend))
//		goto overflow;

//	va->va_start = addr;
//	va->va_end = addr + size;
//	va->vm = NULL;


//	spin_lock(&vmap_area_lock);
//	insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
//	spin_unlock(&vmap_area_lock);

//	BUG_ON(!IS_ALIGNED(va->va_start, align));
//	BUG_ON(va->va_start < vstart);
//	BUG_ON(va->va_end > vend);

//	ret = kasan_populate_vmalloc(addr, size);
//	if (ret) {
//		free_vmap_area(va);
//		return ERR_PTR(ret);
//	}

//	return va;

//overflow:
//	if (!purged) {
//		purge_vmap_area_lazy();
//		purged = 1;
//		goto retry;
//	}

//	if (gfpflags_allow_blocking(gfp_mask)) {
//		unsigned long freed = 0;
//		blocking_notifier_call_chain(&vmap_notify_list, 0, &freed);
//		if (freed > 0) {
//			purged = 0;
//			goto retry;
//		}
//	}

//	if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit())
//		pr_warn("vmap allocation for size %lu failed: use vmalloc=<size> to increase size\n",
//			size);

//	kmem_cache_free(vmap_area_cachep, va);
//	return ERR_PTR(-EBUSY);
//}

//int register_vmap_purge_notifier(struct notifier_block *nb)
//{
//	return blocking_notifier_chain_register(&vmap_notify_list, nb);
//}
//EXPORT_SYMBOL_GPL(register_vmap_purge_notifier);

//int unregister_vmap_purge_notifier(struct notifier_block *nb)
//{
//	return blocking_notifier_chain_unregister(&vmap_notify_list, nb);
//}
//EXPORT_SYMBOL_GPL(unregister_vmap_purge_notifier);

///*
// * lazy_max_pages is the maximum amount of virtual address space we gather up
// * before attempting to purge with a TLB flush.
// *
// * There is a tradeoff here: a larger number will cover more kernel page tables
// * and take slightly longer to purge, but it will linearly reduce the number of
// * global TLB flushes that must be performed. It would seem natural to scale
// * this number up linearly with the number of CPUs (because vmapping activity
// * could also scale linearly with the number of CPUs), however it is likely
// * that in practice, workloads might be constrained in other ways that mean
// * vmap activity will not scale linearly with CPUs. Also, I want to be
// * conservative and not introduce a big latency on huge systems, so go with
// * a less aggressive log scale. It will still be an improvement over the old
// * code, and it will be simple to change the scale factor if we find that it
// * becomes a problem on bigger systems.
// */
//static unsigned long lazy_max_pages(void)
//{
//	unsigned int log;

//	log = fls(num_online_cpus());

//	return log * (32UL * 1024 * 1024 / PAGE_SIZE);
//}

//static atomic_long_t vmap_lazy_nr = ATOMIC_LONG_INIT(0);

///*
// * Serialize vmap purging.  There is no actual criticial section protected
// * by this look, but we want to avoid concurrent calls for performance
// * reasons and to make the pcpu_get_vm_areas more deterministic.
// */
//static DEFINE_MUTEX(vmap_purge_lock);

///* for per-CPU blocks */
//static void purge_fragmented_blocks_allcpus(void);

///*
// * called before a call to iounmap() if the caller wants vm_area_struct's
// * immediately freed.
// */
//void set_iounmap_nonlazy(void)
//{
//	atomic_long_set(&vmap_lazy_nr, lazy_max_pages()+1);
//}

///*
// * Purges all lazily-freed vmap areas.
// */
//static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end)
//{
//	unsigned long resched_threshold;
//	struct llist_node *valist;
//	struct vmap_area *va;
//	struct vmap_area *n_va;

//	lockdep_assert_held(&vmap_purge_lock);

//	valist = llist_del_all(&vmap_purge_list);
//	if (unlikely(valist == NULL))
//		return false;

//	/*
//	 * TODO: to calculate a flush range without looping.
//	 * The list can be up to lazy_max_pages() elements.
//	 */
//	llist_for_each_entry(va, valist, purge_list) {
//		if (va->va_start < start)
//			start = va->va_start;
//		if (va->va_end > end)
//			end = va->va_end;
//	}

//	flush_tlb_kernel_range(start, end);
//	resched_threshold = lazy_max_pages() << 1;

//	spin_lock(&free_vmap_area_lock);
//	llist_for_each_entry_safe(va, n_va, valist, purge_list) {
//		unsigned long nr = (va->va_end - va->va_start) >> PAGE_SHIFT;
//		unsigned long orig_start = va->va_start;
//		unsigned long orig_end = va->va_end;

//		/*
//		 * Finally insert or merge lazily-freed area. It is
//		 * detached and there is no need to "unlink" it from
//		 * anything.
//		 */
//		va = merge_or_add_vmap_area(va, &free_vmap_area_root,
//					    &free_vmap_area_list);

//		if (!va)
//			continue;

//		if (is_vmalloc_or_module_addr((void *)orig_start))
//			kasan_release_vmalloc(orig_start, orig_end,
//					      va->va_start, va->va_end);

//		atomic_long_sub(nr, &vmap_lazy_nr);

//		if (atomic_long_read(&vmap_lazy_nr) < resched_threshold)
//			cond_resched_lock(&free_vmap_area_lock);
//	}
//	spin_unlock(&free_vmap_area_lock);
//	return true;
//}

///*
// * Kick off a purge of the outstanding lazy areas. Don't bother if somebody
// * is already purging.
// */
//static void try_purge_vmap_area_lazy(void)
//{
//	if (mutex_trylock(&vmap_purge_lock)) {
//		__purge_vmap_area_lazy(ULONG_MAX, 0);
//		mutex_unlock(&vmap_purge_lock);
//	}
//}

///*
// * Kick off a purge of the outstanding lazy areas.
// */
//static void purge_vmap_area_lazy(void)
//{
//	mutex_lock(&vmap_purge_lock);
//	purge_fragmented_blocks_allcpus();
//	__purge_vmap_area_lazy(ULONG_MAX, 0);
//	mutex_unlock(&vmap_purge_lock);
//}

///*
// * Free a vmap area, caller ensuring that the area has been unmapped
// * and flush_cache_vunmap had been called for the correct range
// * previously.
// */
//static void free_vmap_area_noflush(struct vmap_area *va)
//{
//	unsigned long nr_lazy;

//	spin_lock(&vmap_area_lock);
//	unlink_va(va, &vmap_area_root);
//	spin_unlock(&vmap_area_lock);

//	nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >>
//				PAGE_SHIFT, &vmap_lazy_nr);

//	/* After this point, we may free va at any time */
//	llist_add(&va->purge_list, &vmap_purge_list);

//	if (unlikely(nr_lazy > lazy_max_pages()))
//		try_purge_vmap_area_lazy();
//}

///*
// * Free and unmap a vmap area
// */
//static void free_unmap_vmap_area(struct vmap_area *va)
//{
//	flush_cache_vunmap(va->va_start, va->va_end);
//	unmap_kernel_range_noflush(va->va_start, va->va_end - va->va_start);
//	if (debug_pagealloc_enabled_static())
//		flush_tlb_kernel_range(va->va_start, va->va_end);

//	free_vmap_area_noflush(va);
//}

//static struct vmap_area *find_vmap_area(unsigned long addr)
//{
//	struct vmap_area *va;

//	spin_lock(&vmap_area_lock);
//	va = __find_vmap_area(addr);
//	spin_unlock(&vmap_area_lock);

//	return va;
//}

///*** Per cpu kva allocator ***/

///*
// * vmap space is limited especially on 32 bit architectures. Ensure there is
// * room for at least 16 percpu vmap blocks per CPU.
// */
///*
// * If we had a constant VMALLOC_START and VMALLOC_END, we'd like to be able
// * to #define VMALLOC_SPACE		(VMALLOC_END-VMALLOC_START). Guess
// * instead (we just need a rough idea)
// */
//#if BITS_PER_LONG == 32
//#define VMALLOC_SPACE		(128UL*1024*1024)
//#else
//#define VMALLOC_SPACE		(128UL*1024*1024*1024)
//#endif

//#define VMALLOC_PAGES		(VMALLOC_SPACE / PAGE_SIZE)
//#define VMAP_MAX_ALLOC		BITS_PER_LONG	/* 256K with 4K pages */
//#define VMAP_BBMAP_BITS_MAX	1024	/* 4MB with 4K pages */
//#define VMAP_BBMAP_BITS_MIN	(VMAP_MAX_ALLOC*2)
//#define VMAP_MIN(x, y)		((x) < (y) ? (x) : (y)) /* can't use min() */
//#define VMAP_MAX(x, y)		((x) > (y) ? (x) : (y)) /* can't use max() */
//#define VMAP_BBMAP_BITS		\
//		VMAP_MIN(VMAP_BBMAP_BITS_MAX,	\
//		VMAP_MAX(VMAP_BBMAP_BITS_MIN,	\
//			VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16))

//#define VMAP_BLOCK_SIZE		(VMAP_BBMAP_BITS * PAGE_SIZE)

//struct vmap_block_queue {
//	spinlock_t lock;
//	struct list_head free;
//};

//struct vmap_block {
//	spinlock_t lock;
//	struct vmap_area *va;
//	unsigned long free, dirty;
//	unsigned long dirty_min, dirty_max; /*< dirty range */
//	struct list_head free_list;
//	struct rcu_head rcu_head;
//	struct list_head purge;
//};

///* Queue of free and dirty vmap blocks, for allocation and flushing purposes */
//static DEFINE_PER_CPU(struct vmap_block_queue, vmap_block_queue);

///*
// * XArray of vmap blocks, indexed by address, to quickly find a vmap block
// * in the free path. Could get rid of this if we change the API to return a
// * "cookie" from alloc, to be passed to free. But no big deal yet.
// */
//static DEFINE_XARRAY(vmap_blocks);

///*
// * We should probably have a fallback mechanism to allocate virtual memory
// * out of partially filled vmap blocks. However vmap block sizing should be
// * fairly reasonable according to the vmalloc size, so it shouldn't be a
// * big problem.
// */

//static unsigned long addr_to_vb_idx(unsigned long addr)
//{
//	addr -= VMALLOC_START & ~(VMAP_BLOCK_SIZE-1);
//	addr /= VMAP_BLOCK_SIZE;
//	return addr;
//}

//static void *vmap_block_vaddr(unsigned long va_start, unsigned long pages_off)
//{
//	unsigned long addr;

//	addr = va_start + (pages_off << PAGE_SHIFT);
//	BUG_ON(addr_to_vb_idx(addr) != addr_to_vb_idx(va_start));
//	return (void *)addr;
//}

///**
// * new_vmap_block - allocates new vmap_block and occupies 2^order pages in this
// *                  block. Of course pages number can't exceed VMAP_BBMAP_BITS
// * @order:    how many 2^order pages should be occupied in newly allocated block
// * @gfp_mask: flags for the page level allocator
// *
// * Return: virtual address in a newly allocated block or ERR_PTR(-errno)
// */
//static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
//{
//	struct vmap_block_queue *vbq;
//	struct vmap_block *vb;
//	struct vmap_area *va;
//	unsigned long vb_idx;
//	int node, err;
//	void *vaddr;

//	node = numa_node_id();

//	vb = kmalloc_node(sizeof(struct vmap_block),
//			gfp_mask & GFP_RECLAIM_MASK, node);
//	if (unlikely(!vb))
//		return ERR_PTR(-ENOMEM);

//	va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE,
//					VMALLOC_START, VMALLOC_END,
//					node, gfp_mask);
//	if (IS_ERR(va)) {
//		kfree(vb);
//		return ERR_CAST(va);
//	}

//	vaddr = vmap_block_vaddr(va->va_start, 0);
//	spin_lock_init(&vb->lock);
//	vb->va = va;
//	/* At least something should be left free */
//	BUG_ON(VMAP_BBMAP_BITS <= (1UL << order));
//	vb->free = VMAP_BBMAP_BITS - (1UL << order);
//	vb->dirty = 0;
//	vb->dirty_min = VMAP_BBMAP_BITS;
//	vb->dirty_max = 0;
//	INIT_LIST_HEAD(&vb->free_list);

//	vb_idx = addr_to_vb_idx(va->va_start);
//	err = xa_insert(&vmap_blocks, vb_idx, vb, gfp_mask);
//	if (err) {
//		kfree(vb);
//		free_vmap_area(va);
//		return ERR_PTR(err);
//	}

//	vbq = &get_cpu_var(vmap_block_queue);
//	spin_lock(&vbq->lock);
//	list_add_tail_rcu(&vb->free_list, &vbq->free);
//	spin_unlock(&vbq->lock);
//	put_cpu_var(vmap_block_queue);

//	return vaddr;
//}

//static void free_vmap_block(struct vmap_block *vb)
//{
//	struct vmap_block *tmp;

//	tmp = xa_erase(&vmap_blocks, addr_to_vb_idx(vb->va->va_start));
//	BUG_ON(tmp != vb);

//	free_vmap_area_noflush(vb->va);
//	kfree_rcu(vb, rcu_head);
//}

//static void purge_fragmented_blocks(int cpu)
//{
//	LIST_HEAD(purge);
//	struct vmap_block *vb;
//	struct vmap_block *n_vb;
//	struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);

//	rcu_read_lock();
//	list_for_each_entry_rcu(vb, &vbq->free, free_list) {

//		if (!(vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS))
//			continue;

//		spin_lock(&vb->lock);
//		if (vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS) {
//			vb->free = 0; /* prevent further allocs after releasing lock */
//			vb->dirty = VMAP_BBMAP_BITS; /* prevent purging it again */
//			vb->dirty_min = 0;
//			vb->dirty_max = VMAP_BBMAP_BITS;
//			spin_lock(&vbq->lock);
//			list_del_rcu(&vb->free_list);
//			spin_unlock(&vbq->lock);
//			spin_unlock(&vb->lock);
//			list_add_tail(&vb->purge, &purge);
//		} else
//			spin_unlock(&vb->lock);
//	}
//	rcu_read_unlock();

//	list_for_each_entry_safe(vb, n_vb, &purge, purge) {
//		list_del(&vb->purge);
//		free_vmap_block(vb);
//	}
//}

//static void purge_fragmented_blocks_allcpus(void)
//{
//	int cpu;

//	for_each_possible_cpu(cpu)
//		purge_fragmented_blocks(cpu);
//}

//static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
//{
//	struct vmap_block_queue *vbq;
//	struct vmap_block *vb;
//	void *vaddr = NULL;
//	unsigned int order;

//	BUG_ON(offset_in_page(size));
//	BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
//	if (WARN_ON(size == 0)) {
//		/*
//		 * Allocating 0 bytes isn't what caller wants since
//		 * get_order(0) returns funny result. Just warn and terminate
//		 * early.
//		 */
//		return NULL;
//	}
//	order = get_order(size);

//	rcu_read_lock();
//	vbq = &get_cpu_var(vmap_block_queue);
//	list_for_each_entry_rcu(vb, &vbq->free, free_list) {
//		unsigned long pages_off;

//		spin_lock(&vb->lock);
//		if (vb->free < (1UL << order)) {
//			spin_unlock(&vb->lock);
//			continue;
//		}

//		pages_off = VMAP_BBMAP_BITS - vb->free;
//		vaddr = vmap_block_vaddr(vb->va->va_start, pages_off);
//		vb->free -= 1UL << order;
//		if (vb->free == 0) {
//			spin_lock(&vbq->lock);
//			list_del_rcu(&vb->free_list);
//			spin_unlock(&vbq->lock);
//		}

//		spin_unlock(&vb->lock);
//		break;
//	}

//	put_cpu_var(vmap_block_queue);
//	rcu_read_unlock();

//	/* Allocate new block if nothing was found */
//	if (!vaddr)
//		vaddr = new_vmap_block(order, gfp_mask);

//	return vaddr;
//}

//static void vb_free(unsigned long addr, unsigned long size)
//{
//	unsigned long offset;
//	unsigned int order;
//	struct vmap_block *vb;

//	BUG_ON(offset_in_page(size));
//	BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);

//	flush_cache_vunmap(addr, addr + size);

//	order = get_order(size);
//	offset = (addr & (VMAP_BLOCK_SIZE - 1)) >> PAGE_SHIFT;
//	vb = xa_load(&vmap_blocks, addr_to_vb_idx(addr));

//	unmap_kernel_range_noflush(addr, size);

//	if (debug_pagealloc_enabled_static())
//		flush_tlb_kernel_range(addr, addr + size);

//	spin_lock(&vb->lock);

//	/* Expand dirty range */
//	vb->dirty_min = min(vb->dirty_min, offset);
//	vb->dirty_max = max(vb->dirty_max, offset + (1UL << order));

//	vb->dirty += 1UL << order;
//	if (vb->dirty == VMAP_BBMAP_BITS) {
//		BUG_ON(vb->free);
//		spin_unlock(&vb->lock);
//		free_vmap_block(vb);
//	} else
//		spin_unlock(&vb->lock);
//}

//static void _vm_unmap_aliases(unsigned long start, unsigned long end, int flush)
//{
//	int cpu;

//	if (unlikely(!vmap_initialized))
//		return;

//	might_sleep();

//	for_each_possible_cpu(cpu) {
//		struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
//		struct vmap_block *vb;

//		rcu_read_lock();
//		list_for_each_entry_rcu(vb, &vbq->free, free_list) {
//			spin_lock(&vb->lock);
//			if (vb->dirty) {
//				unsigned long va_start = vb->va->va_start;
//				unsigned long s, e;

//				s = va_start + (vb->dirty_min << PAGE_SHIFT);
//				e = va_start + (vb->dirty_max << PAGE_SHIFT);

//				start = min(s, start);
//				end   = max(e, end);

//				flush = 1;
//			}
//			spin_unlock(&vb->lock);
//		}
//		rcu_read_unlock();
//	}

//	mutex_lock(&vmap_purge_lock);
//	purge_fragmented_blocks_allcpus();
//	if (!__purge_vmap_area_lazy(start, end) && flush)
//		flush_tlb_kernel_range(start, end);
//	mutex_unlock(&vmap_purge_lock);
//}

///**
// * vm_unmap_aliases - unmap outstanding lazy aliases in the vmap layer
// *
// * The vmap/vmalloc layer lazily flushes kernel virtual mappings primarily
// * to amortize TLB flushing overheads. What this means is that any page you
// * have now, may, in a former life, have been mapped into kernel virtual
// * address by the vmap layer and so there might be some CPUs with TLB entries
// * still referencing that page (additional to the regular 1:1 kernel mapping).
// *
// * vm_unmap_aliases flushes all such lazy mappings. After it returns, we can
// * be sure that none of the pages we have control over will have any aliases
// * from the vmap layer.
// */
//void vm_unmap_aliases(void)
//{
//	unsigned long start = ULONG_MAX, end = 0;
//	int flush = 0;

//	_vm_unmap_aliases(start, end, flush);
//}
//EXPORT_SYMBOL_GPL(vm_unmap_aliases);

///**
// * vm_unmap_ram - unmap linear kernel address space set up by vm_map_ram
// * @mem: the pointer returned by vm_map_ram
// * @count: the count passed to that vm_map_ram call (cannot unmap partial)
// */
//void vm_unmap_ram(const void *mem, unsigned int count)
//{
//	unsigned long size = (unsigned long)count << PAGE_SHIFT;
//	unsigned long addr = (unsigned long)mem;
//	struct vmap_area *va;

//	might_sleep();
//	BUG_ON(!addr);
//	BUG_ON(addr < VMALLOC_START);
//	BUG_ON(addr > VMALLOC_END);
//	BUG_ON(!PAGE_ALIGNED(addr));

//	kasan_poison_vmalloc(mem, size);

//	if (likely(count <= VMAP_MAX_ALLOC)) {
//		debug_check_no_locks_freed(mem, size);
//		vb_free(addr, size);
//		return;
//	}

//	va = find_vmap_area(addr);
//	BUG_ON(!va);
//	debug_check_no_locks_freed((void *)va->va_start,
//				    (va->va_end - va->va_start));
//	free_unmap_vmap_area(va);
//}
//EXPORT_SYMBOL(vm_unmap_ram);

///**
// * vm_map_ram - map pages linearly into kernel virtual address (vmalloc space)
// * @pages: an array of pointers to the pages to be mapped
// * @count: number of pages
// * @node: prefer to allocate data structures on this node
// *
// * If you use this function for less than VMAP_MAX_ALLOC pages, it could be
// * faster than vmap so it's good.  But if you mix long-life and short-life
// * objects with vm_map_ram(), it could consume lots of address space through
// * fragmentation (especially on a 32bit machine).  You could see failures in
// * the end.  Please use this function for short-lived objects.
// *
// * Returns: a pointer to the address that has been mapped, or %NULL on failure
// */
//void *vm_map_ram(struct page **pages, unsigned int count, int node)
//{
//	unsigned long size = (unsigned long)count << PAGE_SHIFT;
//	unsigned long addr;
//	void *mem;

//	if (likely(count <= VMAP_MAX_ALLOC)) {
//		mem = vb_alloc(size, GFP_KERNEL);
//		if (IS_ERR(mem))
//			return NULL;
//		addr = (unsigned long)mem;
//	} else {
//		struct vmap_area *va;
//		va = alloc_vmap_area(size, PAGE_SIZE,
//				VMALLOC_START, VMALLOC_END, node, GFP_KERNEL);
//		if (IS_ERR(va))
//			return NULL;

//		addr = va->va_start;
//		mem = (void *)addr;
//	}

//	kasan_unpoison_vmalloc(mem, size);

//	if (map_kernel_range(addr, size, PAGE_KERNEL, pages) < 0) {
//		vm_unmap_ram(mem, count);
//		return NULL;
//	}
//	return mem;
//}
//EXPORT_SYMBOL(vm_map_ram);

//static struct vm_struct *vmlist __initdata;

///**
// * vm_area_add_early - add vmap area early during boot
// * @vm: vm_struct to add
// *
// * This function is used to add fixed kernel vm area to vmlist before
// * vmalloc_init() is called.  @vm->addr, @vm->size, and @vm->flags
// * should contain proper values and the other fields should be zero.
// *
// * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
// */
//void __init vm_area_add_early(struct vm_struct *vm)
//{
//	struct vm_struct *tmp, **p;

//	BUG_ON(vmap_initialized);
//	for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) {
//		if (tmp->addr >= vm->addr) {
//			BUG_ON(tmp->addr < vm->addr + vm->size);
//			break;
//		} else
//			BUG_ON(tmp->addr + tmp->size > vm->addr);
//	}
//	vm->next = *p;
//	*p = vm;
//}

///**
// * vm_area_register_early - register vmap area early during boot
// * @vm: vm_struct to register
// * @align: requested alignment
// *
// * This function is used to register kernel vm area before
// * vmalloc_init() is called.  @vm->size and @vm->flags should contain
// * proper values on entry and other fields should be zero.  On return,
// * vm->addr contains the allocated address.
// *
// * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
// */
//void __init vm_area_register_early(struct vm_struct *vm, size_t align)
//{
//	static size_t vm_init_off __initdata;
//	unsigned long addr;

//	addr = ALIGN(VMALLOC_START + vm_init_off, align);
//	vm_init_off = PFN_ALIGN(addr + vm->size) - VMALLOC_START;

//	vm->addr = (void *)addr;

//	vm_area_add_early(vm);
//}

//static void vmap_init_free_space(void)
//{
//	unsigned long vmap_start = 1;
//	const unsigned long vmap_end = ULONG_MAX;
//	struct vmap_area *busy, *free;

//	/*
//	 *     B     F     B     B     B     F
//	 * -|-----|.....|-----|-----|-----|.....|-
//	 *  |           The KVA space           |
//	 *  |<--------------------------------->|
//	 */
//	list_for_each_entry(busy, &vmap_area_list, list) {
//		if (busy->va_start - vmap_start > 0) {
//			free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
//			if (!WARN_ON_ONCE(!free)) {
//				free->va_start = vmap_start;
//				free->va_end = busy->va_start;

//				insert_vmap_area_augment(free, NULL,
//					&free_vmap_area_root,
//						&free_vmap_area_list);
//			}
//		}

//		vmap_start = busy->va_end;
//	}

//	if (vmap_end - vmap_start > 0) {
//		free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
//		if (!WARN_ON_ONCE(!free)) {
//			free->va_start = vmap_start;
//			free->va_end = vmap_end;

//			insert_vmap_area_augment(free, NULL,
//				&free_vmap_area_root,
//					&free_vmap_area_list);
//		}
//	}
//}

//void __init vmalloc_init(void)
//{
//	struct vmap_area *va;
//	struct vm_struct *tmp;
//	int i;

//	/*
//	 * Create the cache for vmap_area objects.
//	 */
//	vmap_area_cachep = KMEM_CACHE(vmap_area, SLAB_PANIC);

//	for_each_possible_cpu(i) {
//		struct vmap_block_queue *vbq;
//		struct vfree_deferred *p;

//		vbq = &per_cpu(vmap_block_queue, i);
//		spin_lock_init(&vbq->lock);
//		INIT_LIST_HEAD(&vbq->free);
//		p = &per_cpu(vfree_deferred, i);
//		init_llist_head(&p->list);
//		INIT_WORK(&p->wq, free_work);
//	}

//	/* Import existing vmlist entries. */
//	for (tmp = vmlist; tmp; tmp = tmp->next) {
//		va = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
//		if (WARN_ON_ONCE(!va))
//			continue;

//		va->va_start = (unsigned long)tmp->addr;
//		va->va_end = va->va_start + tmp->size;
//		va->vm = tmp;
//		insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
//	}

//	/*
//	 * Now we can initialize a free vmap space.
//	 */
//	vmap_init_free_space();
//	vmap_initialized = true;
//}

///**
// * unmap_kernel_range - unmap kernel VM area and flush cache and TLB
// * @addr: start of the VM area to unmap
// * @size: size of the VM area to unmap
// *
// * Similar to unmap_kernel_range_noflush() but flushes vcache before
// * the unmapping and tlb after.
// */
//void unmap_kernel_range(unsigned long addr, unsigned long size)
//{
//	unsigned long end = addr + size;

//	flush_cache_vunmap(addr, end);
//	unmap_kernel_range_noflush(addr, size);
//	flush_tlb_kernel_range(addr, end);
//}

//static inline void setup_vmalloc_vm_locked(struct vm_struct *vm,
//	struct vmap_area *va, unsigned long flags, const void *caller)
//{
//	vm->flags = flags;
//	vm->addr = (void *)va->va_start;
//	vm->size = va->va_end - va->va_start;
//	vm->caller = caller;
//	va->vm = vm;
//}

//static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
//			      unsigned long flags, const void *caller)
//{
//	spin_lock(&vmap_area_lock);
//	setup_vmalloc_vm_locked(vm, va, flags, caller);
//	spin_unlock(&vmap_area_lock);
//}

//static void clear_vm_uninitialized_flag(struct vm_struct *vm)
//{
//	/*
//	 * Before removing VM_UNINITIALIZED,
//	 * we should make sure that vm has proper values.
//	 * Pair with smp_rmb() in show_numa_info().
//	 */
//	smp_wmb();
//	vm->flags &= ~VM_UNINITIALIZED;
//}

//static struct vm_struct *__get_vm_area_node(unsigned long size,
//		unsigned long align, unsigned long flags, unsigned long start,
//		unsigned long end, int node, gfp_t gfp_mask, const void *caller)
//{
//	struct vmap_area *va;
//	struct vm_struct *area;
//	unsigned long requested_size = size;

//	BUG_ON(in_interrupt());
//	size = PAGE_ALIGN(size);
//	if (unlikely(!size))
//		return NULL;

//	if (flags & VM_IOREMAP)
//		align = 1ul << clamp_t(int, get_count_order_long(size),
//				       PAGE_SHIFT, IOREMAP_MAX_ORDER);

//	area = kzalloc_node(sizeof(*area), gfp_mask & GFP_RECLAIM_MASK, node);
//	if (unlikely(!area))
//		return NULL;

//	if (!(flags & VM_NO_GUARD))
//		size += PAGE_SIZE;

//	va = alloc_vmap_area(size, align, start, end, node, gfp_mask);
//	if (IS_ERR(va)) {
//		kfree(area);
//		return NULL;
//	}

//	kasan_unpoison_vmalloc((void *)va->va_start, requested_size);

//	setup_vmalloc_vm(area, va, flags, caller);

//	return area;
//}

//struct vm_struct *__get_vm_area_caller(unsigned long size, unsigned long flags,
//				       unsigned long start, unsigned long end,
//				       const void *caller)
//{
//	return __get_vm_area_node(size, 1, flags, start, end, NUMA_NO_NODE,
//				  GFP_KERNEL, caller);
//}

///**
// * get_vm_area - reserve a contiguous kernel virtual area
// * @size:	 size of the area
// * @flags:	 %VM_IOREMAP for I/O mappings or VM_ALLOC
// *
// * Search an area of @size in the kernel virtual mapping area,
// * and reserved it for out purposes.  Returns the area descriptor
// * on success or %NULL on failure.
// *
// * Return: the area descriptor on success or %NULL on failure.
// */
//struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
//{
//	return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,
//				  NUMA_NO_NODE, GFP_KERNEL,
//				  __builtin_return_address(0));
//}

//struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
//				const void *caller)
//{
//	return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,
//				  NUMA_NO_NODE, GFP_KERNEL, caller);
//}

///**
// * find_vm_area - find a continuous kernel virtual area
// * @addr:	  base address
// *
// * Search for the kernel VM area starting at @addr, and return it.
// * It is up to the caller to do all required locking to keep the returned
// * pointer valid.
// *
// * Return: the area descriptor on success or %NULL on failure.
// */
//struct vm_struct *find_vm_area(const void *addr)
//{
//	struct vmap_area *va;

//	va = find_vmap_area((unsigned long)addr);
//	if (!va)
//		return NULL;

//	return va->vm;
//}

///**
// * remove_vm_area - find and remove a continuous kernel virtual area
// * @addr:	    base address
// *
// * Search for the kernel VM area starting at @addr, and remove it.
// * This function returns the found VM area, but using it is NOT safe
// * on SMP machines, except for its size or flags.
// *
// * Return: the area descriptor on success or %NULL on failure.
// */
//struct vm_struct *remove_vm_area(const void *addr)
//{
//	struct vmap_area *va;

//	might_sleep();

//	spin_lock(&vmap_area_lock);
//	va = __find_vmap_area((unsigned long)addr);
//	if (va && va->vm) {
//		struct vm_struct *vm = va->vm;

//		va->vm = NULL;
//		spin_unlock(&vmap_area_lock);

//		kasan_free_shadow(vm);
//		free_unmap_vmap_area(va);

//		return vm;
//	}

//	spin_unlock(&vmap_area_lock);
//	return NULL;
//}

//static inline void set_area_direct_map(const struct vm_struct *area,
//				       int (*set_direct_map)(struct page *page))
//{
//	int i;

//	for (i = 0; i < area->nr_pages; i++)
//		if (page_address(area->pages[i]))
//			set_direct_map(area->pages[i]);
//}

///* Handle removing and resetting vm mappings related to the vm_struct. */
//static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages)
//{
//	unsigned long start = ULONG_MAX, end = 0;
//	int flush_reset = area->flags & VM_FLUSH_RESET_PERMS;
//	int flush_dmap = 0;
//	int i;

//	remove_vm_area(area->addr);

//	/* If this is not VM_FLUSH_RESET_PERMS memory, no need for the below. */
//	if (!flush_reset)
//		return;

//	/*
//	 * If not deallocating pages, just do the flush of the VM area and
//	 * return.
//	 */
//	if (!deallocate_pages) {
//		vm_unmap_aliases();
//		return;
//	}

//	/*
//	 * If execution gets here, flush the vm mapping and reset the direct
//	 * map. Find the start and end range of the direct mappings to make sure
//	 * the vm_unmap_aliases() flush includes the direct map.
//	 */
//	for (i = 0; i < area->nr_pages; i++) {
//		unsigned long addr = (unsigned long)page_address(area->pages[i]);
//		if (addr) {
//			start = min(addr, start);
//			end = max(addr + PAGE_SIZE, end);
//			flush_dmap = 1;
//		}
//	}

//	/*
//	 * Set direct map to something invalid so that it won't be cached if
//	 * there are any accesses after the TLB flush, then flush the TLB and
//	 * reset the direct map permissions to the default.
//	 */
//	set_area_direct_map(area, set_direct_map_invalid_noflush);
//	_vm_unmap_aliases(start, end, flush_dmap);
//	set_area_direct_map(area, set_direct_map_default_noflush);
//}

//static void __vunmap(const void *addr, int deallocate_pages)
//{
//	struct vm_struct *area;

//	if (!addr)
//		return;

//	if (WARN(!PAGE_ALIGNED(addr), "Trying to vfree() bad address (%p)\n",
//			addr))
//		return;

//	area = find_vm_area(addr);
//	if (unlikely(!area)) {
//		WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
//				addr);
//		return;
//	}

//	debug_check_no_locks_freed(area->addr, get_vm_area_size(area));
//	debug_check_no_obj_freed(area->addr, get_vm_area_size(area));

//	kasan_poison_vmalloc(area->addr, get_vm_area_size(area));

//	vm_remove_mappings(area, deallocate_pages);

//	if (deallocate_pages) {
//		int i;

//		for (i = 0; i < area->nr_pages; i++) {
//			struct page *page = area->pages[i];

//			BUG_ON(!page);
//			__free_pages(page, 0);
//		}
//		atomic_long_sub(area->nr_pages, &nr_vmalloc_pages);

//		kvfree(area->pages);
//	}

//	kfree(area);
//	return;
//}

//static inline void __vfree_deferred(const void *addr)
//{
//	/*
//	 * Use raw_cpu_ptr() because this can be called from preemptible
//	 * context. Preemption is absolutely fine here, because the llist_add()
//	 * implementation is lockless, so it works even if we are adding to
//	 * another cpu's list. schedule_work() should be fine with this too.
//	 */
//	struct vfree_deferred *p = raw_cpu_ptr(&vfree_deferred);

//	if (llist_add((struct llist_node *)addr, &p->list))
//		schedule_work(&p->wq);
//}

///**
// * vfree_atomic - release memory allocated by vmalloc()
// * @addr:	  memory base address
// *
// * This one is just like vfree() but can be called in any atomic context
// * except NMIs.
// */
//void vfree_atomic(const void *addr)
//{
//	BUG_ON(in_nmi());

//	kmemleak_free(addr);

//	if (!addr)
//		return;
//	__vfree_deferred(addr);
//}

//static void __vfree(const void *addr)
//{
//	if (unlikely(in_interrupt()))
//		__vfree_deferred(addr);
//	else
//		__vunmap(addr, 1);
//}

///**
// * vfree - Release memory allocated by vmalloc()
// * @addr:  Memory base address
// *
// * Free the virtually continuous memory area starting at @addr, as obtained
// * from one of the vmalloc() family of APIs.  This will usually also free the
// * physical memory underlying the virtual allocation, but that memory is
// * reference counted, so it will not be freed until the last user goes away.
// *
// * If @addr is NULL, no operation is performed.
// *
// * Context:
// * May sleep if called *not* from interrupt context.
// * Must not be called in NMI context (strictly speaking, it could be
// * if we have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, but making the calling
// * conventions for vfree() arch-depenedent would be a really bad idea).
// */
//void vfree(const void *addr)
//{
//	BUG_ON(in_nmi());

//	kmemleak_free(addr);

//	might_sleep_if(!in_interrupt());

//	if (!addr)
//		return;

//	__vfree(addr);
//}
//EXPORT_SYMBOL(vfree);

///**
// * vunmap - release virtual mapping obtained by vmap()
// * @addr:   memory base address
// *
// * Free the virtually contiguous memory area starting at @addr,
// * which was created from the page array passed to vmap().
// *
// * Must not be called in interrupt context.
// */
//void vunmap(const void *addr)
//{
//	BUG_ON(in_interrupt());
//	might_sleep();
//	if (addr)
//		__vunmap(addr, 0);
//}
//EXPORT_SYMBOL(vunmap);

///**
// * vmap - map an array of pages into virtually contiguous space
// * @pages: array of page pointers
// * @count: number of pages to map
// * @flags: vm_area->flags
// * @prot: page protection for the mapping
// *
// * Maps @count pages from @pages into contiguous kernel virtual space.
// * If @flags contains %VM_MAP_PUT_PAGES the ownership of the pages array itself
// * (which must be kmalloc or vmalloc memory) and one reference per pages in it
// * are transferred from the caller to vmap(), and will be freed / dropped when
// * vfree() is called on the return value.
// *
// * Return: the address of the area or %NULL on failure
// */
//void *vmap(struct page **pages, unsigned int count,
//	   unsigned long flags, pgprot_t prot)
//{
//	struct vm_struct *area;
//	unsigned long size;		/* In bytes */

//	might_sleep();

//	if (count > totalram_pages())
//		return NULL;

//	size = (unsigned long)count << PAGE_SHIFT;
//	area = get_vm_area_caller(size, flags, __builtin_return_address(0));
//	if (!area)
//		return NULL;

//	if (map_kernel_range((unsigned long)area->addr, size, pgprot_nx(prot),
//			pages) < 0) {
//		vunmap(area->addr);
//		return NULL;
//	}

//	if (flags & VM_MAP_PUT_PAGES) {
//		area->pages = pages;
//		area->nr_pages = count;
//	}
//	return area->addr;
//}
//EXPORT_SYMBOL(vmap);

//#ifdef CONFIG_VMAP_PFN
//struct vmap_pfn_data {
//	unsigned long	*pfns;
//	pgprot_t	prot;
//	unsigned int	idx;
//};

//static int vmap_pfn_apply(pte_t *pte, unsigned long addr, void *private)
//{
//	struct vmap_pfn_data *data = private;

//	if (WARN_ON_ONCE(pfn_valid(data->pfns[data->idx])))
//		return -EINVAL;
//	*pte = pte_mkspecial(pfn_pte(data->pfns[data->idx++], data->prot));
//	return 0;
//}

///**
// * vmap_pfn - map an array of PFNs into virtually contiguous space
// * @pfns: array of PFNs
// * @count: number of pages to map
// * @prot: page protection for the mapping
// *
// * Maps @count PFNs from @pfns into contiguous kernel virtual space and returns
// * the start address of the mapping.
// */
//void *vmap_pfn(unsigned long *pfns, unsigned int count, pgprot_t prot)
//{
//	struct vmap_pfn_data data = { .pfns = pfns, .prot = pgprot_nx(prot) };
//	struct vm_struct *area;

//	area = get_vm_area_caller(count * PAGE_SIZE, VM_IOREMAP,
//			__builtin_return_address(0));
//	if (!area)
//		return NULL;
//	if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
//			count * PAGE_SIZE, vmap_pfn_apply, &data)) {
//		free_vm_area(area);
//		return NULL;
//	}
//	return area->addr;
//}
//EXPORT_SYMBOL_GPL(vmap_pfn);
//#endif /* CONFIG_VMAP_PFN */

//static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
//				 pgprot_t prot, int node)
//{
//	const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
//	unsigned int nr_pages = get_vm_area_size(area) >> PAGE_SHIFT;
//	unsigned int array_size = nr_pages * sizeof(struct page *), i;
//	struct page **pages;

//	gfp_mask |= __GFP_NOWARN;
//	if (!(gfp_mask & (GFP_DMA | GFP_DMA32)))
//		gfp_mask |= __GFP_HIGHMEM;

//	/* Please note that the recursion is strictly bounded. */
//	if (array_size > PAGE_SIZE) {
//		pages = __vmalloc_node(array_size, 1, nested_gfp, node,
//					area->caller);
//	} else {
//		pages = kmalloc_node(array_size, nested_gfp, node);
//	}

//	if (!pages) {
//		remove_vm_area(area->addr);
//		kfree(area);
//		return NULL;
//	}

//	area->pages = pages;
//	area->nr_pages = nr_pages;

//	for (i = 0; i < area->nr_pages; i++) {
//		struct page *page;

//		if (node == NUMA_NO_NODE)
//			page = alloc_page(gfp_mask);
//		else
//			page = alloc_pages_node(node, gfp_mask, 0);

//		if (unlikely(!page)) {
//			/* Successfully allocated i pages, free them in __vfree() */
//			area->nr_pages = i;
//			atomic_long_add(area->nr_pages, &nr_vmalloc_pages);
//			goto fail;
//		}
//		area->pages[i] = page;
//		if (gfpflags_allow_blocking(gfp_mask))
//			cond_resched();
//	}
//	atomic_long_add(area->nr_pages, &nr_vmalloc_pages);

//	if (map_kernel_range((unsigned long)area->addr, get_vm_area_size(area),
//			prot, pages) < 0)
//		goto fail;

//	return area->addr;

//fail:
//	warn_alloc(gfp_mask, NULL,
//			  "vmalloc: allocation failure, allocated %ld of %ld bytes",
//			  (area->nr_pages*PAGE_SIZE), area->size);
//	__vfree(area->addr);
//	return NULL;
//}

///**
// * __vmalloc_node_range - allocate virtually contiguous memory
// * @size:		  allocation size
// * @align:		  desired alignment
// * @start:		  vm area range start
// * @end:		  vm area range end
// * @gfp_mask:		  flags for the page level allocator
// * @prot:		  protection mask for the allocated pages
// * @vm_flags:		  additional vm area flags (e.g. %VM_NO_GUARD)
// * @node:		  node to use for allocation or NUMA_NO_NODE
// * @caller:		  caller's return address
// *
// * Allocate enough pages to cover @size from the page level
// * allocator with @gfp_mask flags.  Map them into contiguous
// * kernel virtual space, using a pagetable protection of @prot.
// *
// * Return: the address of the area or %NULL on failure
// */
//void *__vmalloc_node_range(unsigned long size, unsigned long align,
//			unsigned long start, unsigned long end, gfp_t gfp_mask,
//			pgprot_t prot, unsigned long vm_flags, int node,
//			const void *caller)
//{
//	struct vm_struct *area;
//	void *addr;
//	unsigned long real_size = size;

//	size = PAGE_ALIGN(size);
//	if (!size || (size >> PAGE_SHIFT) > totalram_pages())
//		goto fail;

//	area = __get_vm_area_node(real_size, align, VM_ALLOC | VM_UNINITIALIZED |
//				vm_flags, start, end, node, gfp_mask, caller);
//	if (!area)
//		goto fail;

//	addr = __vmalloc_area_node(area, gfp_mask, prot, node);
//	if (!addr)
//		return NULL;

//	/*
//	 * In this function, newly allocated vm_struct has VM_UNINITIALIZED
//	 * flag. It means that vm_struct is not fully initialized.
//	 * Now, it is fully initialized, so remove this flag here.
//	 */
//	clear_vm_uninitialized_flag(area);

//	kmemleak_vmalloc(area, size, gfp_mask);

//	return addr;

//fail:
//	warn_alloc(gfp_mask, NULL,
//			  "vmalloc: allocation failure: %lu bytes", real_size);
//	return NULL;
//}

/**
 * __vmalloc_node - allocate virtually contiguous memory
 * @size:	    allocation size
 * @align:	    desired alignment
 * @gfp_mask:	    flags for the page level allocator
 * @node:	    node to use for allocation or NUMA_NO_NODE
 * @caller:	    caller's return address
 *
 * Allocate enough pages to cover @size from the page level allocator with
 * @gfp_mask flags.  Map them into contiguous kernel virtual space.
 *
 * Reclaim modifiers in @gfp_mask - __GFP_NORETRY, __GFP_RETRY_MAYFAIL
 * and __GFP_NOFAIL are not supported
 *
 * Any use of gfp flags outside of GFP_KERNEL should be consulted
 * with mm people.
 *
 * Return: pointer to the allocated memory or %NULL on error
 */
void *__vmalloc_node(unsigned long size, unsigned long align,
			    gfp_t gfp_mask, int node, const void *caller)
{
	return __kmalloc(size, gfp_mask);
}
///*
// * This is only for performance analysis of vmalloc and stress purpose.
// * It is required by vmalloc test module, therefore do not use it other
// * than that.
// */
//#ifdef CONFIG_TEST_VMALLOC_MODULE
//EXPORT_SYMBOL_GPL(__vmalloc_node);
//#endif

//void *__vmalloc(unsigned long size, gfp_t gfp_mask)
//{
//	return __vmalloc_node(size, 1, gfp_mask, NUMA_NO_NODE,
//				__builtin_return_address(0));
//}
//EXPORT_SYMBOL(__vmalloc);

///**
// * vmalloc - allocate virtually contiguous memory
// * @size:    allocation size
// *
// * Allocate enough pages to cover @size from the page level
// * allocator and map them into contiguous kernel virtual space.
// *
// * For tight control over page level allocator and protection flags
// * use __vmalloc() instead.
// *
// * Return: pointer to the allocated memory or %NULL on error
// */
//void *vmalloc(unsigned long size)
//{
//	return __vmalloc_node(size, 1, GFP_KERNEL, NUMA_NO_NODE,
//				__builtin_return_address(0));
//}
//EXPORT_SYMBOL(vmalloc);

///**
// * vzalloc - allocate virtually contiguous memory with zero fill
// * @size:    allocation size
// *
// * Allocate enough pages to cover @size from the page level
// * allocator and map them into contiguous kernel virtual space.
// * The memory allocated is set to zero.
// *
// * For tight control over page level allocator and protection flags
// * use __vmalloc() instead.
// *
// * Return: pointer to the allocated memory or %NULL on error
// */
//void *vzalloc(unsigned long size)
//{
//	return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_ZERO, NUMA_NO_NODE,
//				__builtin_return_address(0));
//}
//EXPORT_SYMBOL(vzalloc);

///**
// * vmalloc_user - allocate zeroed virtually contiguous memory for userspace
// * @size: allocation size
// *
// * The resulting memory area is zeroed so it can be mapped to userspace
// * without leaking data.
// *
// * Return: pointer to the allocated memory or %NULL on error
// */
//void *vmalloc_user(unsigned long size)
//{
//	return __vmalloc_node_range(size, SHMLBA,  VMALLOC_START, VMALLOC_END,
//				    GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL,
//				    VM_USERMAP, NUMA_NO_NODE,
//				    __builtin_return_address(0));
//}
//EXPORT_SYMBOL(vmalloc_user);

///**
// * vmalloc_node - allocate memory on a specific node
// * @size:	  allocation size
// * @node:	  numa node
// *
// * Allocate enough pages to cover @size from the page level
// * allocator and map them into contiguous kernel virtual space.
// *
// * For tight control over page level allocator and protection flags
// * use __vmalloc() instead.
// *
// * Return: pointer to the allocated memory or %NULL on error
// */
//void *vmalloc_node(unsigned long size, int node)
//{
//	return __vmalloc_node(size, 1, GFP_KERNEL, node,
//			__builtin_return_address(0));
//}
//EXPORT_SYMBOL(vmalloc_node);

///**
// * vzalloc_node - allocate memory on a specific node with zero fill
// * @size:	allocation size
// * @node:	numa node
// *
// * Allocate enough pages to cover @size from the page level
// * allocator and map them into contiguous kernel virtual space.
// * The memory allocated is set to zero.
// *
// * Return: pointer to the allocated memory or %NULL on error
// */
//void *vzalloc_node(unsigned long size, int node)
//{
//	return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_ZERO, node,
//				__builtin_return_address(0));
//}
//EXPORT_SYMBOL(vzalloc_node);

//#if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)
//#define GFP_VMALLOC32 (GFP_DMA32 | GFP_KERNEL)
//#elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
//#define GFP_VMALLOC32 (GFP_DMA | GFP_KERNEL)
//#else
///*
// * 64b systems should always have either DMA or DMA32 zones. For others
// * GFP_DMA32 should do the right thing and use the normal zone.
// */
//#define GFP_VMALLOC32 GFP_DMA32 | GFP_KERNEL
//#endif

///**
// * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
// * @size:	allocation size
// *
// * Allocate enough 32bit PA addressable pages to cover @size from the
// * page level allocator and map them into contiguous kernel virtual space.
// *
// * Return: pointer to the allocated memory or %NULL on error
// */
//void *vmalloc_32(unsigned long size)
//{
//	return __vmalloc_node(size, 1, GFP_VMALLOC32, NUMA_NO_NODE,
//			__builtin_return_address(0));
//}
//EXPORT_SYMBOL(vmalloc_32);

///**
// * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
// * @size:	     allocation size
// *
// * The resulting memory area is 32bit addressable and zeroed so it can be
// * mapped to userspace without leaking data.
// *
// * Return: pointer to the allocated memory or %NULL on error
// */
//void *vmalloc_32_user(unsigned long size)
//{
//	return __vmalloc_node_range(size, SHMLBA,  VMALLOC_START, VMALLOC_END,
//				    GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL,
//				    VM_USERMAP, NUMA_NO_NODE,
//				    __builtin_return_address(0));
//}
//EXPORT_SYMBOL(vmalloc_32_user);

///*
// * small helper routine , copy contents to buf from addr.
// * If the page is not present, fill zero.
// */

//static int aligned_vread(char *buf, char *addr, unsigned long count)
//{
//	struct page *p;
//	int copied = 0;

//	while (count) {
//		unsigned long offset, length;

//		offset = offset_in_page(addr);
//		length = PAGE_SIZE - offset;
//		if (length > count)
//			length = count;
//		p = vmalloc_to_page(addr);
//		/*
//		 * To do safe access to this _mapped_ area, we need
//		 * lock. But adding lock here means that we need to add
//		 * overhead of vmalloc()/vfree() calles for this _debug_
//		 * interface, rarely used. Instead of that, we'll use
//		 * kmap() and get small overhead in this access function.
//		 */
//		if (p) {
//			/*
//			 * we can expect USER0 is not used (see vread/vwrite's
//			 * function description)
//			 */
//			void *map = kmap_atomic(p);
//			memcpy(buf, map + offset, length);
//			kunmap_atomic(map);
//		} else
//			memset(buf, 0, length);

//		addr += length;
//		buf += length;
//		copied += length;
//		count -= length;
//	}
//	return copied;
//}

//static int aligned_vwrite(char *buf, char *addr, unsigned long count)
//{
//	struct page *p;
//	int copied = 0;

//	while (count) {
//		unsigned long offset, length;

//		offset = offset_in_page(addr);
//		length = PAGE_SIZE - offset;
//		if (length > count)
//			length = count;
//		p = vmalloc_to_page(addr);
//		/*
//		 * To do safe access to this _mapped_ area, we need
//		 * lock. But adding lock here means that we need to add
//		 * overhead of vmalloc()/vfree() calles for this _debug_
//		 * interface, rarely used. Instead of that, we'll use
//		 * kmap() and get small overhead in this access function.
//		 */
//		if (p) {
//			/*
//			 * we can expect USER0 is not used (see vread/vwrite's
//			 * function description)
//			 */
//			void *map = kmap_atomic(p);
//			memcpy(map + offset, buf, length);
//			kunmap_atomic(map);
//		}
//		addr += length;
//		buf += length;
//		copied += length;
//		count -= length;
//	}
//	return copied;
//}

///**
// * vread() - read vmalloc area in a safe way.
// * @buf:     buffer for reading data
// * @addr:    vm address.
// * @count:   number of bytes to be read.
// *
// * This function checks that addr is a valid vmalloc'ed area, and
// * copy data from that area to a given buffer. If the given memory range
// * of [addr...addr+count) includes some valid address, data is copied to
// * proper area of @buf. If there are memory holes, they'll be zero-filled.
// * IOREMAP area is treated as memory hole and no copy is done.
// *
// * If [addr...addr+count) doesn't includes any intersects with alive
// * vm_struct area, returns 0. @buf should be kernel's buffer.
// *
// * Note: In usual ops, vread() is never necessary because the caller
// * should know vmalloc() area is valid and can use memcpy().
// * This is for routines which have to access vmalloc area without
// * any information, as /dev/kmem.
// *
// * Return: number of bytes for which addr and buf should be increased
// * (same number as @count) or %0 if [addr...addr+count) doesn't
// * include any intersection with valid vmalloc area
// */
//long vread(char *buf, char *addr, unsigned long count)
//{
//	struct vmap_area *va;
//	struct vm_struct *vm;
//	char *vaddr, *buf_start = buf;
//	unsigned long buflen = count;
//	unsigned long n;

//	/* Don't allow overflow */
//	if ((unsigned long) addr + count < count)
//		count = -(unsigned long) addr;

//	spin_lock(&vmap_area_lock);
//	list_for_each_entry(va, &vmap_area_list, list) {
//		if (!count)
//			break;

//		if (!va->vm)
//			continue;

//		vm = va->vm;
//		vaddr = (char *) vm->addr;
//		if (addr >= vaddr + get_vm_area_size(vm))
//			continue;
//		while (addr < vaddr) {
//			if (count == 0)
//				goto finished;
//			*buf = '\0';
//			buf++;
//			addr++;
//			count--;
//		}
//		n = vaddr + get_vm_area_size(vm) - addr;
//		if (n > count)
//			n = count;
//		if (!(vm->flags & VM_IOREMAP))
//			aligned_vread(buf, addr, n);
//		else /* IOREMAP area is treated as memory hole */
//			memset(buf, 0, n);
//		buf += n;
//		addr += n;
//		count -= n;
//	}
//finished:
//	spin_unlock(&vmap_area_lock);

//	if (buf == buf_start)
//		return 0;
//	/* zero-fill memory holes */
//	if (buf != buf_start + buflen)
//		memset(buf, 0, buflen - (buf - buf_start));

//	return buflen;
//}

///**
// * vwrite() - write vmalloc area in a safe way.
// * @buf:      buffer for source data
// * @addr:     vm address.
// * @count:    number of bytes to be read.
// *
// * This function checks that addr is a valid vmalloc'ed area, and
// * copy data from a buffer to the given addr. If specified range of
// * [addr...addr+count) includes some valid address, data is copied from
// * proper area of @buf. If there are memory holes, no copy to hole.
// * IOREMAP area is treated as memory hole and no copy is done.
// *
// * If [addr...addr+count) doesn't includes any intersects with alive
// * vm_struct area, returns 0. @buf should be kernel's buffer.
// *
// * Note: In usual ops, vwrite() is never necessary because the caller
// * should know vmalloc() area is valid and can use memcpy().
// * This is for routines which have to access vmalloc area without
// * any information, as /dev/kmem.
// *
// * Return: number of bytes for which addr and buf should be
// * increased (same number as @count) or %0 if [addr...addr+count)
// * doesn't include any intersection with valid vmalloc area
// */
//long vwrite(char *buf, char *addr, unsigned long count)
//{
//	struct vmap_area *va;
//	struct vm_struct *vm;
//	char *vaddr;
//	unsigned long n, buflen;
//	int copied = 0;

//	/* Don't allow overflow */
//	if ((unsigned long) addr + count < count)
//		count = -(unsigned long) addr;
//	buflen = count;

//	spin_lock(&vmap_area_lock);
//	list_for_each_entry(va, &vmap_area_list, list) {
//		if (!count)
//			break;

//		if (!va->vm)
//			continue;

//		vm = va->vm;
//		vaddr = (char *) vm->addr;
//		if (addr >= vaddr + get_vm_area_size(vm))
//			continue;
//		while (addr < vaddr) {
//			if (count == 0)
//				goto finished;
//			buf++;
//			addr++;
//			count--;
//		}
//		n = vaddr + get_vm_area_size(vm) - addr;
//		if (n > count)
//			n = count;
//		if (!(vm->flags & VM_IOREMAP)) {
//			aligned_vwrite(buf, addr, n);
//			copied++;
//		}
//		buf += n;
//		addr += n;
//		count -= n;
//	}
//finished:
//	spin_unlock(&vmap_area_lock);
//	if (!copied)
//		return 0;
//	return buflen;
//}

///**
// * remap_vmalloc_range_partial - map vmalloc pages to userspace
// * @vma:		vma to cover
// * @uaddr:		target user address to start at
// * @kaddr:		virtual address of vmalloc kernel memory
// * @pgoff:		offset from @kaddr to start at
// * @size:		size of map area
// *
// * Returns:	0 for success, -Exxx on failure
// *
// * This function checks that @kaddr is a valid vmalloc'ed area,
// * and that it is big enough to cover the range starting at
// * @uaddr in @vma. Will return failure if that criteria isn't
// * met.
// *
// * Similar to remap_pfn_range() (see mm/memory.c)
// */
//int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr,
//				void *kaddr, unsigned long pgoff,
//				unsigned long size)
//{
//	struct vm_struct *area;
//	unsigned long off;
//	unsigned long end_index;

//	if (check_shl_overflow(pgoff, PAGE_SHIFT, &off))
//		return -EINVAL;

//	size = PAGE_ALIGN(size);

//	if (!PAGE_ALIGNED(uaddr) || !PAGE_ALIGNED(kaddr))
//		return -EINVAL;

//	area = find_vm_area(kaddr);
//	if (!area)
//		return -EINVAL;

//	if (!(area->flags & (VM_USERMAP | VM_DMA_COHERENT)))
//		return -EINVAL;

//	if (check_add_overflow(size, off, &end_index) ||
//	    end_index > get_vm_area_size(area))
//		return -EINVAL;
//	kaddr += off;

//	do {
//		struct page *page = vmalloc_to_page(kaddr);
//		int ret;

//		ret = vm_insert_page(vma, uaddr, page);
//		if (ret)
//			return ret;

//		uaddr += PAGE_SIZE;
//		kaddr += PAGE_SIZE;
//		size -= PAGE_SIZE;
//	} while (size > 0);

//	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;

//	return 0;
//}
//EXPORT_SYMBOL(remap_vmalloc_range_partial);

///**
// * remap_vmalloc_range - map vmalloc pages to userspace
// * @vma:		vma to cover (map full range of vma)
// * @addr:		vmalloc memory
// * @pgoff:		number of pages into addr before first page to map
// *
// * Returns:	0 for success, -Exxx on failure
// *
// * This function checks that addr is a valid vmalloc'ed area, and
// * that it is big enough to cover the vma. Will return failure if
// * that criteria isn't met.
// *
// * Similar to remap_pfn_range() (see mm/memory.c)
// */
//int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
//						unsigned long pgoff)
//{
//	return remap_vmalloc_range_partial(vma, vma->vm_start,
//					   addr, pgoff,
//					   vma->vm_end - vma->vm_start);
//}
//EXPORT_SYMBOL(remap_vmalloc_range);

//void free_vm_area(struct vm_struct *area)
//{
//	struct vm_struct *ret;
//	ret = remove_vm_area(area->addr);
//	BUG_ON(ret != area);
//	kfree(area);
//}
//EXPORT_SYMBOL_GPL(free_vm_area);

//#ifdef CONFIG_SMP
//static struct vmap_area *node_to_va(struct rb_node *n)
//{
//	return rb_entry_safe(n, struct vmap_area, rb_node);
//}

///**
// * pvm_find_va_enclose_addr - find the vmap_area @addr belongs to
// * @addr: target address
// *
// * Returns: vmap_area if it is found. If there is no such area
// *   the first highest(reverse order) vmap_area is returned
// *   i.e. va->va_start < addr && va->va_end < addr or NULL
// *   if there are no any areas before @addr.
// */
//static struct vmap_area *
//pvm_find_va_enclose_addr(unsigned long addr)
//{
//	struct vmap_area *va, *tmp;
//	struct rb_node *n;

//	n = free_vmap_area_root.rb_node;
//	va = NULL;

//	while (n) {
//		tmp = rb_entry(n, struct vmap_area, rb_node);
//		if (tmp->va_start <= addr) {
//			va = tmp;
//			if (tmp->va_end >= addr)
//				break;

//			n = n->rb_right;
//		} else {
//			n = n->rb_left;
//		}
//	}

//	return va;
//}

///**
// * pvm_determine_end_from_reverse - find the highest aligned address
// * of free block below VMALLOC_END
// * @va:
// *   in - the VA we start the search(reverse order);
// *   out - the VA with the highest aligned end address.
// *
// * Returns: determined end address within vmap_area
// */
//static unsigned long
//pvm_determine_end_from_reverse(struct vmap_area **va, unsigned long align)
//{
//	unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
//	unsigned long addr;

//	if (likely(*va)) {
//		list_for_each_entry_from_reverse((*va),
//				&free_vmap_area_list, list) {
//			addr = min((*va)->va_end & ~(align - 1), vmalloc_end);
//			if ((*va)->va_start < addr)
//				return addr;
//		}
//	}

//	return 0;
//}

///**
// * pcpu_get_vm_areas - allocate vmalloc areas for percpu allocator
// * @offsets: array containing offset of each area
// * @sizes: array containing size of each area
// * @nr_vms: the number of areas to allocate
// * @align: alignment, all entries in @offsets and @sizes must be aligned to this
// *
// * Returns: kmalloc'd vm_struct pointer array pointing to allocated
// *	    vm_structs on success, %NULL on failure
// *
// * Percpu allocator wants to use congruent vm areas so that it can
// * maintain the offsets among percpu areas.  This function allocates
// * congruent vmalloc areas for it with GFP_KERNEL.  These areas tend to
// * be scattered pretty far, distance between two areas easily going up
// * to gigabytes.  To avoid interacting with regular vmallocs, these
// * areas are allocated from top.
// *
// * Despite its complicated look, this allocator is rather simple. It
// * does everything top-down and scans free blocks from the end looking
// * for matching base. While scanning, if any of the areas do not fit the
// * base address is pulled down to fit the area. Scanning is repeated till
// * all the areas fit and then all necessary data structures are inserted
// * and the result is returned.
// */
//struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
//				     const size_t *sizes, int nr_vms,
//				     size_t align)
//{
//	const unsigned long vmalloc_start = ALIGN(VMALLOC_START, align);
//	const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
//	struct vmap_area **vas, *va;
//	struct vm_struct **vms;
//	int area, area2, last_area, term_area;
//	unsigned long base, start, size, end, last_end, orig_start, orig_end;
//	bool purged = false;
//	enum fit_type type;

//	/* verify parameters and allocate data structures */
//	BUG_ON(offset_in_page(align) || !is_power_of_2(align));
//	for (last_area = 0, area = 0; area < nr_vms; area++) {
//		start = offsets[area];
//		end = start + sizes[area];

//		/* is everything aligned properly? */
//		BUG_ON(!IS_ALIGNED(offsets[area], align));
//		BUG_ON(!IS_ALIGNED(sizes[area], align));

//		/* detect the area with the highest address */
//		if (start > offsets[last_area])
//			last_area = area;

//		for (area2 = area + 1; area2 < nr_vms; area2++) {
//			unsigned long start2 = offsets[area2];
//			unsigned long end2 = start2 + sizes[area2];

//			BUG_ON(start2 < end && start < end2);
//		}
//	}
//	last_end = offsets[last_area] + sizes[last_area];

//	if (vmalloc_end - vmalloc_start < last_end) {
//		WARN_ON(true);
//		return NULL;
//	}

//	vms = kcalloc(nr_vms, sizeof(vms[0]), GFP_KERNEL);
//	vas = kcalloc(nr_vms, sizeof(vas[0]), GFP_KERNEL);
//	if (!vas || !vms)
//		goto err_free2;

//	for (area = 0; area < nr_vms; area++) {
//		vas[area] = kmem_cache_zalloc(vmap_area_cachep, GFP_KERNEL);
//		vms[area] = kzalloc(sizeof(struct vm_struct), GFP_KERNEL);
//		if (!vas[area] || !vms[area])
//			goto err_free;
//	}
//retry:
//	spin_lock(&free_vmap_area_lock);

//	/* start scanning - we scan from the top, begin with the last area */
//	area = term_area = last_area;
//	start = offsets[area];
//	end = start + sizes[area];

//	va = pvm_find_va_enclose_addr(vmalloc_end);
//	base = pvm_determine_end_from_reverse(&va, align) - end;

//	while (true) {
//		/*
//		 * base might have underflowed, add last_end before
//		 * comparing.
//		 */
//		if (base + last_end < vmalloc_start + last_end)
//			goto overflow;

//		/*
//		 * Fitting base has not been found.
//		 */
//		if (va == NULL)
//			goto overflow;

//		/*
//		 * If required width exceeds current VA block, move
//		 * base downwards and then recheck.
//		 */
//		if (base + end > va->va_end) {
//			base = pvm_determine_end_from_reverse(&va, align) - end;
//			term_area = area;
//			continue;
//		}

//		/*
//		 * If this VA does not fit, move base downwards and recheck.
//		 */
//		if (base + start < va->va_start) {
//			va = node_to_va(rb_prev(&va->rb_node));
//			base = pvm_determine_end_from_reverse(&va, align) - end;
//			term_area = area;
//			continue;
//		}

//		/*
//		 * This area fits, move on to the previous one.  If
//		 * the previous one is the terminal one, we're done.
//		 */
//		area = (area + nr_vms - 1) % nr_vms;
//		if (area == term_area)
//			break;

//		start = offsets[area];
//		end = start + sizes[area];
//		va = pvm_find_va_enclose_addr(base + end);
//	}

//	/* we've found a fitting base, insert all va's */
//	for (area = 0; area < nr_vms; area++) {
//		int ret;

//		start = base + offsets[area];
//		size = sizes[area];

//		va = pvm_find_va_enclose_addr(start);
//		if (WARN_ON_ONCE(va == NULL))
//			/* It is a BUG(), but trigger recovery instead. */
//			goto recovery;

//		type = classify_va_fit_type(va, start, size);
//		if (WARN_ON_ONCE(type == NOTHING_FIT))
//			/* It is a BUG(), but trigger recovery instead. */
//			goto recovery;

//		ret = adjust_va_to_fit_type(va, start, size, type);
//		if (unlikely(ret))
//			goto recovery;

//		/* Allocated area. */
//		va = vas[area];
//		va->va_start = start;
//		va->va_end = start + size;
//	}

//	spin_unlock(&free_vmap_area_lock);

//	/* populate the kasan shadow space */
//	for (area = 0; area < nr_vms; area++) {
//		if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area]))
//			goto err_free_shadow;

//		kasan_unpoison_vmalloc((void *)vas[area]->va_start,
//				       sizes[area]);
//	}

//	/* insert all vm's */
//	spin_lock(&vmap_area_lock);
//	for (area = 0; area < nr_vms; area++) {
//		insert_vmap_area(vas[area], &vmap_area_root, &vmap_area_list);

//		setup_vmalloc_vm_locked(vms[area], vas[area], VM_ALLOC,
//				 pcpu_get_vm_areas);
//	}
//	spin_unlock(&vmap_area_lock);

//	kfree(vas);
//	return vms;

//recovery:
//	/*
//	 * Remove previously allocated areas. There is no
//	 * need in removing these areas from the busy tree,
//	 * because they are inserted only on the final step
//	 * and when pcpu_get_vm_areas() is success.
//	 */
//	while (area--) {
//		orig_start = vas[area]->va_start;
//		orig_end = vas[area]->va_end;
//		va = merge_or_add_vmap_area(vas[area], &free_vmap_area_root,
//					    &free_vmap_area_list);
//		if (va)
//			kasan_release_vmalloc(orig_start, orig_end,
//				va->va_start, va->va_end);
//		vas[area] = NULL;
//	}

//overflow:
//	spin_unlock(&free_vmap_area_lock);
//	if (!purged) {
//		purge_vmap_area_lazy();
//		purged = true;

//		/* Before "retry", check if we recover. */
//		for (area = 0; area < nr_vms; area++) {
//			if (vas[area])
//				continue;

//			vas[area] = kmem_cache_zalloc(
//				vmap_area_cachep, GFP_KERNEL);
//			if (!vas[area])
//				goto err_free;
//		}

//		goto retry;
//	}

//err_free:
//	for (area = 0; area < nr_vms; area++) {
//		if (vas[area])
//			kmem_cache_free(vmap_area_cachep, vas[area]);

//		kfree(vms[area]);
//	}
//err_free2:
//	kfree(vas);
//	kfree(vms);
//	return NULL;

//err_free_shadow:
//	spin_lock(&free_vmap_area_lock);
//	/*
//	 * We release all the vmalloc shadows, even the ones for regions that
//	 * hadn't been successfully added. This relies on kasan_release_vmalloc
//	 * being able to tolerate this case.
//	 */
//	for (area = 0; area < nr_vms; area++) {
//		orig_start = vas[area]->va_start;
//		orig_end = vas[area]->va_end;
//		va = merge_or_add_vmap_area(vas[area], &free_vmap_area_root,
//					    &free_vmap_area_list);
//		if (va)
//			kasan_release_vmalloc(orig_start, orig_end,
//				va->va_start, va->va_end);
//		vas[area] = NULL;
//		kfree(vms[area]);
//	}
//	spin_unlock(&free_vmap_area_lock);
//	kfree(vas);
//	kfree(vms);
//	return NULL;
//}

///**
// * pcpu_free_vm_areas - free vmalloc areas for percpu allocator
// * @vms: vm_struct pointer array returned by pcpu_get_vm_areas()
// * @nr_vms: the number of allocated areas
// *
// * Free vm_structs and the array allocated by pcpu_get_vm_areas().
// */
//void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
//{
//	int i;

//	for (i = 0; i < nr_vms; i++)
//		free_vm_area(vms[i]);
//	kfree(vms);
//}
//#endif	/* CONFIG_SMP */

//#ifdef CONFIG_PROC_FS
//static void *s_start(struct seq_file *m, loff_t *pos)
//	__acquires(&vmap_purge_lock)
//	__acquires(&vmap_area_lock)
//{
//	mutex_lock(&vmap_purge_lock);
//	spin_lock(&vmap_area_lock);

//	return seq_list_start(&vmap_area_list, *pos);
//}

//static void *s_next(struct seq_file *m, void *p, loff_t *pos)
//{
//	return seq_list_next(p, &vmap_area_list, pos);
//}

//static void s_stop(struct seq_file *m, void *p)
//	__releases(&vmap_area_lock)
//	__releases(&vmap_purge_lock)
//{
//	spin_unlock(&vmap_area_lock);
//	mutex_unlock(&vmap_purge_lock);
//}

//static void show_numa_info(struct seq_file *m, struct vm_struct *v)
//{
//	if (IS_ENABLED(CONFIG_NUMA)) {
//		unsigned int nr, *counters = m->private;

//		if (!counters)
//			return;

//		if (v->flags & VM_UNINITIALIZED)
//			return;
//		/* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
//		smp_rmb();

//		memset(counters, 0, nr_node_ids * sizeof(unsigned int));

//		for (nr = 0; nr < v->nr_pages; nr++)
//			counters[page_to_nid(v->pages[nr])]++;

//		for_each_node_state(nr, N_HIGH_MEMORY)
//			if (counters[nr])
//				seq_printf(m, " N%u=%u", nr, counters[nr]);
//	}
//}

//static void show_purge_info(struct seq_file *m)
//{
//	struct llist_node *head;
//	struct vmap_area *va;

//	head = READ_ONCE(vmap_purge_list.first);
//	if (head == NULL)
//		return;

//	llist_for_each_entry(va, head, purge_list) {
//		seq_printf(m, "0x%pK-0x%pK %7ld unpurged vm_area\n",
//			(void *)va->va_start, (void *)va->va_end,
//			va->va_end - va->va_start);
//	}
//}

//static int s_show(struct seq_file *m, void *p)
//{
//	struct vmap_area *va;
//	struct vm_struct *v;

//	va = list_entry(p, struct vmap_area, list);

//	/*
//	 * s_show can encounter race with remove_vm_area, !vm on behalf
//	 * of vmap area is being tear down or vm_map_ram allocation.
//	 */
//	if (!va->vm) {
//		seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n",
//			(void *)va->va_start, (void *)va->va_end,
//			va->va_end - va->va_start);

//		return 0;
//	}

//	v = va->vm;

//	seq_printf(m, "0x%pK-0x%pK %7ld",
//		v->addr, v->addr + v->size, v->size);

//	if (v->caller)
//		seq_printf(m, " %pS", v->caller);

//	if (v->nr_pages)
//		seq_printf(m, " pages=%d", v->nr_pages);

//	if (v->phys_addr)
//		seq_printf(m, " phys=%pa", &v->phys_addr);

//	if (v->flags & VM_IOREMAP)
//		seq_puts(m, " ioremap");

//	if (v->flags & VM_ALLOC)
//		seq_puts(m, " vmalloc");

//	if (v->flags & VM_MAP)
//		seq_puts(m, " vmap");

//	if (v->flags & VM_USERMAP)
//		seq_puts(m, " user");

//	if (v->flags & VM_DMA_COHERENT)
//		seq_puts(m, " dma-coherent");

//	if (is_vmalloc_addr(v->pages))
//		seq_puts(m, " vpages");

//	show_numa_info(m, v);
//	seq_putc(m, '\n');

//	/*
//	 * As a final step, dump "unpurged" areas. Note,
//	 * that entire "/proc/vmallocinfo" output will not
//	 * be address sorted, because the purge list is not
//	 * sorted.
//	 */
//	if (list_is_last(&va->list, &vmap_area_list))
//		show_purge_info(m);

//	return 0;
//}

//static const struct seq_operations vmalloc_op = {
//	.start = s_start,
//	.next = s_next,
//	.stop = s_stop,
//	.show = s_show,
//};

//static int __init proc_vmalloc_init(void)
//{
//	if (IS_ENABLED(CONFIG_NUMA))
//		proc_create_seq_private("vmallocinfo", 0400, NULL,
//				&vmalloc_op,
//				nr_node_ids * sizeof(unsigned int), NULL);
//	else
//		proc_create_seq("vmallocinfo", 0400, NULL, &vmalloc_op);
//	return 0;
//}
//module_init(proc_vmalloc_init);

//#endif
